--compile_one_dependency suggestion should not trigger when source files are picked up by wildcards

6087f5d94779558ca044420a195547054db58a02 added a warning that triggers when building or testing the all the targets in any real-life package. E.g.,
```
$ cat BUILD
cc_test(
name = 't',
srcs = ['a.cc', 'b.cc']
)
$ bazel build //:*
WARNING: BUILD: //:BUILD is a source file, nothing will be built for it. If you want to build a target that consumes this file, try --compile_one_dependency
WARNING: BUILD:1:8: //:b.cc is a source file, nothing will be built for it. If you want to build a target that consumes this file, try --compile_one_dependency
WARNING:BUILD:1:8: //:a.cc is a source file, nothing will be built for it. If you want to build a target that consumes this file, try --compile_one_dependency
```
I suggest that is excessive.

Reproduce the warning with the BUILD example and `bazel build //:*`; then trace the warning behavior introduced by commit 6087f5d94779558ca044420a195547054db58a02. Done means wildcard expansion no longer suggests `--compile_one_dependency` for source files consumed by matching targets, while the intended warning remains for genuinely unbuildable source targets.

Written by the indexing model from the issue text.