Build failure when importing `github.com/grpc-ecosystem/go-grpc-middleware/testing/testproto` in tests

### What version of rules_go are you using?

`v0.28.0`

### What version of gazelle are you using?

`v0.23.0`

### What version of Bazel are you using?

`4.2.1`

### Does this issue reproduce with the latest releases of all the above?

They are the latest releases

### What operating system and processor architecture are you using?

linux/amd64

### Any other potentially useful information about your toolchain?

### What did you do?

When import `github.com/grpc-ecosystem/go-grpc-middleware/testing/testproto` in tests, bazel will complain about package name mismatch:

```
external/com_github_grpc_ecosystem_go_grpc_middleware/testing/testproto/test.manual_extractfields.pb.go:3:9: package mwitkow_testproto; expected testproto
external/com_github_grpc_ecosystem_go_grpc_middleware/testing/testproto/test.manual_validator.pb.go:3:9: package mwitkow_testproto; expected testproto
```

This is a minimal reproducible example:

initial files:

`go.mod`:
```go
module test

go 1.17

require github.com/grpc-ecosystem/go-grpc-middleware v1.3.0

require (
github.com/golang/protobuf v1.4.3 // indirect
golang.org/x/net v0.0.0-20201021035429-f5854403a974 // indirect
golang.org/x/sys v0.0.0-20210615035016-665e8c7367d1 // indirect
golang.org/x/text v0.3.3 // indirect
google.golang.org/genproto v0.0.0-20200526211855-cb27e3aa2013 // indirect
google.golang.org/grpc v1.40.0 // indirect
google.golang.org/protobuf v1.25.0 // indirect
)
```

`main.go`:
```go
package main

import (
"fmt"
)

func main() {
fmt.Println("vim-go")
}
```

`main_test.go`:
```go
package main

import (
"testing"

pb "github.com/grpc-ecosystem/go-grpc-middleware/testing/testproto"
)

func TestDummy(t *testing.T) {
var _ = pb.RegisterTestServiceServer
}
```

`WORKSPACE`:
```starlark
workspace(name = "test")

load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")

GO_VERSION = "1.17.1"

# For rules_go
RULES_GO_VERSION = "v0.28.0"

http_archive(
name = "io_bazel_rules_go",
sha256 = "8e968b5fcea1d2d64071872b12737bbb5514524ee5f0a4f54f5920266c261acb",
urls = [
"https://mirror.bazel.build/github.com/bazelbuild/rules_go/releases/download/%s/rules_go-%s.zip" % (RULES_GO_VERSION, RULES_GO_VERSION),
"https://github.com/bazelbuild/rules_go/releases/download/%s/rules_go-%s.zip" % (RULES_GO_VERSION, RULES_GO_VERSION),
],
)

# For gazelle
GAZELLE_VERSION = "v0.23.0"

http_archive(
name = "bazel_gazelle",
sha256 = "62ca106be173579c0a167deb23358fdfe71ffa1e4cfdddf5582af26520f1c66f",
urls = [
"https://storage.googleapis.com/bazel-mirror/github.com/bazelbuild/bazel-gazelle/releases/download/%s/bazel-gazelle-%s.tar.gz" % (GAZELLE_VERSION, GAZELLE_VERSION),
"https://github.com/bazelbuild/bazel-gazelle/releases/download/%s/bazel-gazelle-%s.tar.gz" % (GAZELLE_VERSION, GAZELLE_VERSION),
],
)

load("@io_bazel_rules_go//go:deps.bzl", "go_register_toolchains", "go_rules_dependencies")
load("@bazel_gazelle//:deps.bzl", "gazelle_dependencies")

go_rules_dependencies()

go_register_toolchains(version = GO_VERSION)

gazelle_dependencies()

load("//:external.bzl", "go_dependencies")

# gazelle:repository_macro external.bzl%go_dependencies
go_dependencies()

load("@bazel_tools//tools/build_defs/repo:git.bzl", "git_repository")

git_repository(
name = "com_google_protobuf",
# actual: tag = "v3.14.0",
commit = "2514f0bd7da7e2af1bed4c5d1b84f031c4d12c10",
remote = "https://github.com/protocolbuffers/protobuf",
shallow_since = "1605300819 -0800",
)

load("@com_google_protobuf//:protobuf_deps.bzl", "protobuf_deps")

protobuf_deps()
```

`BUILD.bazel`:
```starlark
load("@bazel_gazelle//:def.bzl", "gazelle")

# gazelle:prefix test
gazelle(name = "gazelle")
```

`external.bzl`:
```starlark
def go_dependencies(): pass
```

Then run the following commands to populate the files:
```
$ go mod tidy
$ bazel run //:gazelle -- update-repos -from_file=go.mod -prune -to_macro=external.bzl%go_dependencies
$ bazel run //:gazelle -- fix
```

`go test` works:
```
$ go test
PASS
ok test 0.003s
```

but `bazel test //:test_test` does not:
```
$ bazel test //:test_test --sandbox_debug
INFO: Analyzed target //:test_test (0 packages loaded, 0 targets configured).
INFO: Found 1 test target...
ERROR: /home/fishy/.cache/bazel/_bazel_fishy/66988687ae8da86da8a81c193b210e82/external/com_github_grpc_ecosystem_go_grpc_middleware/testing/testproto/BUILD.bazel:19:11: GoCompilePkg external/com_github_grpc_ecosystem_go_grpc_middleware/testing/testproto/testproto.a failed: (Exit 1): linux-sandbox failed: error executing command
(cd /home/fishy/.cache/bazel/_bazel_fishy/66988687ae8da86da8a81c193b210e82/sandbox/linux-sandbox/1826/execroot/test && \
exec env - \
CGO_ENABLED=1 \
GOARCH=amd64 \
GOOS=linux \
GOPATH='' \
GOROOT=external/go_sdk \
GOROOT_FINAL=GOROOT \
PATH=/usr/bin:/bin \
TMPDIR=/tmp \
/home/fishy/.cache/bazel/_bazel_fishy/install/ee8d7e4b6774884ed2cd0aece6fc9fda/linux-sandbox -t 15 -w /home/fishy/.cache/bazel/_bazel_fishy/66988687ae8da86da8a81c193b210e82/sandbox/linux-sandbox/1826/execroot/test -w /tmp -w /dev/shm -D -- bazel-out/host/bin/external/go_sdk/builder compilepkg -sdk external/go_sdk -installsuffix linux_amd64 -src bazel-out/k8-fastbuild/bin/external/com_github_grpc_ecosystem_go_grpc_middleware/testing/testproto/mwitkow_testproto_go_proto_/github.com/grpc-ecosystem/go-grpc-middleware/testing/testproto/test.pb.go -src external/com_github_grpc_ecosystem_go_grpc_middleware/testing/testproto/test.manual_extractfields.pb.go -src external/com_github_grpc_ecosystem_go_grpc_middleware/testing/testproto/test.manual_validator.pb.go -arc 'github.com/golang/protobuf/proto=github.com/golang/protobuf/proto=bazel-out/k8-fastbuild/bin/external/com_github_golang_protobuf/proto/proto.x' -arc 'google.golang.org/protobuf/proto=google.golang.org/protobuf/proto=bazel-out/k8-fastbuild/bin/external/org_golang_google_protobuf/proto/proto.x' -arc 'google.golang.org/protobuf/reflect/protoreflect=google.golang.org/protobuf/reflect/protoreflect=bazel-out/k8-fastbuild/bin/external/org_golang_google_protobuf/reflect/protoreflect/protoreflect.x' -arc 'google.golang.org/protobuf/runtime/protoiface=google.golang.org/protobuf/runtime/protoiface=bazel-out/k8-fastbuild/bin/external/org_golang_google_protobuf/runtime/protoiface/protoiface.x' -arc 'google.golang.org/protobuf/runtime/protoimpl=google.golang.org/protobuf/runtime/protoimpl=bazel-out/k8-fastbuild/bin/external/org_golang_google_protobuf/runtime/protoimpl/protoimpl.x' -arc 'google.golang.org/protobuf/types/descriptorpb=google.golang.org/protobuf/types/descriptorpb=bazel-out/k8-fastbuild/bin/external/org_golang_google_protobuf/types/descriptorpb/descriptorpb.x' -arc 'google.golang.org/protobuf/types/known/anypb=google.golang.org/protobuf/types/known/anypb=bazel-out/k8-fastbuild/bin/external/org_golang_google_protobuf/types/known/anypb/anypb.x' -arc 'google.golang.org/protobuf/types/known/apipb=google.golang.org/protobuf/types/known/apipb=bazel-out/k8-fastbuild/bin/external/org_golang_google_protobuf/types/known/apipb/apipb.x' -arc 'google.golang.org/protobuf/types/known/durationpb=google.golang.org/protobuf/types/known/durationpb=bazel-out/k8-fastbuild/bin/external/org_golang_google_protobuf/types/known/durationpb/durationpb.x' -arc 'google.golang.org/protobuf/types/known/emptypb=google.golang.org/protobuf/types/known/emptypb=bazel-out/k8-fastbuild/bin/external/org_golang_google_protobuf/types/known/emptypb/emptypb.x' -arc 'google.golang.org/protobuf/types/known/fieldmaskpb=google.golang.org/protobuf/types/known/fieldmaskpb=bazel-out/k8-fastbuild/bin/external/org_golang_google_protobuf/types/known/fieldmaskpb/fieldmaskpb.x' -arc 'google.golang.org/protobuf/types/known/sourcecontextpb=google.golang.org/protobuf/types/known/sourcecontextpb=bazel-out/k8-fastbuild/bin/external/org_golang_google_protobuf/types/known/sourcecontextpb/sourcecontextpb.x' -arc 'google.golang.org/protobuf/types/known/structpb=google.golang.org/protobuf/types/known/structpb=bazel-out/k8-fastbuild/bin/external/org_golang_google_protobuf/types/known/structpb/structpb.x' -arc 'google.golang.org/protobuf/types/known/timestamppb=google.golang.org/protobuf/types/known/timestamppb=bazel-out/k8-fastbuild/bin/external/org_golang_google_protobuf/types/known/timestamppb/timestamppb.x' -arc 'google.golang.org/protobuf/types/known/typepb=google.golang.org/protobuf/types/known/typepb=bazel-out/k8-fastbuild/bin/external/org_golang_google_protobuf/types/known/typepb/typepb.x' -arc 'google.golang.org/protobuf/types/known/wrapperspb=google.golang.org/protobuf/types/known/wrapperspb=bazel-out/k8-fastbuild/bin/external/org_golang_google_protobuf/types/known/wrapperspb/wrapperspb.x' -arc 'google.golang.org/protobuf/types/pluginpb=google.golang.org/protobuf/types/pluginpb=bazel-out/k8-fastbuild/bin/external/org_golang_google_protobuf/types/pluginpb/pluginpb.x' -arc 'google.golang.org/grpc=google.golang.org/grpc=bazel-out/k8-fastbuild/bin/external/org_golang_google_grpc/grpc.x' -arc 'google.golang.org/grpc/codes=google.golang.org/grpc/codes=bazel-out/k8-fastbuild/bin/external/org_golang_google_grpc/codes/codes.x' -arc 'google.golang.org/grpc/status=google.golang.org/grpc/status=bazel-out/k8-fastbuild/bin/external/org_golang_google_grpc/status/status.x' -arc 'golang.org/x/net/context=golang.org/x/net/context=bazel-out/k8-fastbuild/bin/external/org_golang_x_net/context/context.x' -importpath github.com/grpc-ecosystem/go-grpc-middleware/testing/testproto -p github.com/grpc-ecosystem/go-grpc-middleware/testing/testproto -package_list bazel-out/host/bin/external/go_sdk/packages.txt -o bazel-out/k8-fastbuild/bin/external/com_github_grpc_ecosystem_go_grpc_middleware/testing/testproto/testproto.a -x bazel-out/k8-fastbuild/bin/external/com_github_grpc_ecosystem_go_grpc_middleware/testing/testproto/testproto.x -gcflags '' -asmflags '')
1632937200.103469910: src/main/tools/linux-sandbox.cc:152: calling pipe(2)...
1632937200.103489794: src/main/tools/linux-sandbox.cc:171: calling clone(2)...
1632937200.103624986: src/main/tools/linux-sandbox.cc:180: linux-sandbox-pid1 has PID 142268
1632937200.103670020: src/main/tools/linux-sandbox-pid1.cc:447: Pid1Main started
1632937200.103760408: src/main/tools/linux-sandbox.cc:197: done manipulating pipes
1632937200.103798470: src/main/tools/linux-sandbox-pid1.cc:189: working dir: /home/fishy/.cache/bazel/_bazel_fishy/66988687ae8da86da8a81c193b210e82/sandbox/linux-sandbox/1826/execroot/test
1632937200.103808083: src/main/tools/linux-sandbox-pid1.cc:221: writable: /home/fishy/.cache/bazel/_bazel_fishy/66988687ae8da86da8a81c193b210e82/sandbox/linux-sandbox/1826/execroot/test
1632937200.103812853: src/main/tools/linux-sandbox-pid1.cc:221: writable: /tmp
1632937200.103817025: src/main/tools/linux-sandbox-pid1.cc:221: writable: /dev/shm
1632937200.103852624: src/main/tools/linux-sandbox-pid1.cc:292: remount ro: /
1632937200.103857943: src/main/tools/linux-sandbox-pid1.cc:292: remount ro: /dev
1632937200.103861579: src/main/tools/linux-sandbox-pid1.cc:292: remount ro: /dev/pts
1632937200.103864975: src/main/tools/linux-sandbox-pid1.cc:292: remount rw: /dev/shm
1632937200.103868471: src/main/tools/linux-sandbox-pid1.cc:292: remount ro: /dev/mqueue
1632937200.103871514: src/main/tools/linux-sandbox-pid1.cc:292: remount ro: /dev/hugepages
1632937200.103875039: src/main/tools/linux-sandbox-pid1.cc:292: remount ro: /run
1632937200.103878408: src/main/tools/linux-sandbox-pid1.cc:292: remount ro: /run/lock
1632937200.103881968: src/main/tools/linux-sandbox-pid1.cc:292: remount ro: /run/user/1000
1632937200.103885657: src/main/tools/linux-sandbox-pid1.cc:292: remount ro: /sys
1632937200.103888768: src/main/tools/linux-sandbox-pid1.cc:292: remount ro: /sys/kernel/security
1632937200.103894017: src/main/tools/linux-sandbox-pid1.cc:292: remount ro: /sys/fs/cgroup
1632937200.103897968: src/main/tools/linux-sandbox-pid1.cc:292: remount ro: /sys/fs/pstore
1632937200.103916805: src/main/tools/linux-sandbox-pid1.cc:292: remount ro: /sys/firmware/efi/efivars
1632937200.103921807: src/main/tools/linux-sandbox-pid1.cc:292: remount ro: /sys/fs/bpf
1632937200.103925266: src/main/tools/linux-sandbox-pid1.cc:292: remount ro: /sys/kernel/debug
1632937200.103928767: src/main/tools/linux-sandbox-pid1.cc:292: remount ro: /sys/kernel/tracing
1632937200.103932468: src/main/tools/linux-sandbox-pid1.cc:292: remount ro: /sys/kernel/config
1632937200.103936045: src/main/tools/linux-sandbox-pid1.cc:292: remount ro: /sys/fs/fuse/connections
1632937200.103940417: src/main/tools/linux-sandbox-pid1.cc:292: remount ro: /proc
1632937200.103943816: src/main/tools/linux-sandbox-pid1.cc:292: remount ro: /proc/sys/fs/binfmt_misc
1632937200.103948705: src/main/tools/linux-sandbox-pid1.cc:313: remount(nullptr, /proc/sys/fs/binfmt_misc, nullptr, 2101281, nullptr) failure (Operation not permitted) ignored
1632937200.103954992: src/main/tools/linux-sandbox-pid1.cc:292: remount ro: /proc/sys/fs/binfmt_misc
1632937200.103958586: src/main/tools/linux-sandbox-pid1.cc:292: remount ro: /boot
1632937200.103962061: src/main/tools/linux-sandbox-pid1.cc:292: remount ro: /boot/efi
1632937200.103965452: src/main/tools/linux-sandbox-pid1.cc:292: remount ro: /home/fishy/.mnt/gdrive
1632937200.103973659: src/main/tools/linux-sandbox-pid1.cc:292: remount ro: /home/fishy/GoogleDrive/rclone
1632937200.103977799: src/main/tools/linux-sandbox-pid1.cc:292: remount rw: /home/fishy/.cache/bazel/_bazel_fishy/66988687ae8da86da8a81c193b210e82/sandbox/linux-sandbox/1826/execroot/test
1632937200.103981364: src/main/tools/linux-sandbox-pid1.cc:292: remount rw: /home/fishy/.cache/bazel/_bazel_fishy/66988687ae8da86da8a81c193b210e82/sandbox/linux-sandbox/1826/execroot/test
1632937200.103984673: src/main/tools/linux-sandbox-pid1.cc:292: remount rw: /tmp
1632937200.103987843: src/main/tools/linux-sandbox-pid1.cc:292: remount rw: /dev/shm
1632937200.104011643: src/main/tools/linux-sandbox-pid1.cc:376: calling fork...
1632937200.104082268: src/main/tools/linux-sandbox-pid1.cc:406: child started with PID 2
external/com_github_grpc_ecosystem_go_grpc_middleware/testing/testproto/test.manual_extractfields.pb.go:3:9: package mwitkow_testproto; expected testproto
external/com_github_grpc_ecosystem_go_grpc_middleware/testing/testproto/test.manual_validator.pb.go:3:9: package mwitkow_testproto; expected testproto
compilepkg: error running subcommand external/go_sdk/pkg/tool/linux_amd64/compile: exit status 2
1632937200.124095073: src/main/tools/linux-sandbox-pid1.cc:423: wait returned pid=2, status=0x100
1632937200.124105378: src/main/tools/linux-sandbox-pid1.cc:441: child exited normally with code 1
1632937200.124323157: src/main/tools/linux-sandbox.cc:233: child exited normally with code 1
Target //:test_test failed to build
Use --verbose_failures to see the command lines of failed build steps.
INFO: Elapsed time: 0.160s, Critical Path: 0.03s
INFO: 2 processes: 2 internal.
FAILED: Build did NOT complete successfully
//:test_test FAILED TO BUILD

FAILED: Build did NOT complete successfully
```

This seems to only break in test files (I tried to remove `main_test.go` and import it in `main.go` instead and didn't trigger the problem)

### What did you expect to see?

### What did you see instead?

Start with the minimal reproduction in WORKSPACE, external.bzl, BUILD.bazel, and main_test.go. Run go test and bazel test //:test_test, then inspect the generated external/com_github_grpc_ecosystem_go_grpc_middleware/testing/testproto/BUILD.bazel and the package-name error. Done means the Bazel test succeeds when importing testproto, as the Go test already does.

Written by the indexing model from the issue text.