release-26.2: pkg/kv/followerreads/followerreads_test: TestSecondaryTenantFollowerReadsRouting failed

pkg/kv/followerreads/followerreads_test.TestSecondaryTenantFollowerReadsRouting [failed](https://teamcity.cockroachdb.com/buildConfiguration/Cockroach_Ci_TestsAwsLinuxArm64_UnitTests/21476216?buildTab=log) with [artifacts](https://teamcity.cockroachdb.com/buildConfiguration/Cockroach_Ci_TestsAwsLinuxArm64_UnitTests/21476216?buildTab=artifacts#/) on release-26.2 @ [72b6d4ebccb45cf7e611b102e9ea4571968a496c](https://github.com/cockroachdb/cockroach/commits/72b6d4ebccb45cf7e611b102e9ea4571968a496c):

```
=== RUN TestSecondaryTenantFollowerReadsRouting
test_log_scope.go:172: test logs captured to: /artifacts/tmp/_tmp/5b4c6b77bb1c4afd2098de9e97c144fb/logTestSecondaryTenantFollowerReadsRouting3470141456
test_log_scope.go:82: use -show-logs to present logs inline
--- FAIL: TestSecondaryTenantFollowerReadsRouting (7.09s)
panic: runtime error: invalid memory address or nil pointer dereference [recovered, repanicked]
[signal SIGSEGV: segmentation violation code=0x1 addr=0x59 pc=0x44af314]

goroutine 36991 [running]:
testing.tRunner.func1.2({0x4cac760, 0xa232990})
GOROOT/src/testing/testing.go:1872 +0x19c
testing.tRunner.func1()
GOROOT/src/testing/testing.go:1875 +0x31c
panic({0x4cac760?, 0xa232990?})
GOROOT/src/runtime/panic.go:783 +0x120
github.com/cockroachdb/cockroach/pkg/util/stop.(*Stopper).recover(0x4006cff788?, {0x68fcf00, 0xa7e44e0})
pkg/util/stop/stopper.go:226 +0x68
panic({0x4cac760?, 0xa232990?})
GOROOT/src/runtime/panic.go:783 +0x120
github.com/cockroachdb/cockroach/pkg/util/stop.(*Stopper).Stop(0x4016798090, {0x68fcf00, 0xa7e44e0})
pkg/util/stop/stopper.go:575 +0x14c
panic({0x4cac760?, 0xa232990?})
GOROOT/src/runtime/panic.go:783 +0x120
github.com/cockroachdb/cockroach/pkg/server.(*testTenant).DistSenderI(0x4017701720?)
pkg/server/testserver.go:1144 +0x4
pkg/kv/followerreads/followerreads_test_test.TestSecondaryTenantFollowerReadsRouting.func1(0x4014282000)
pkg/kv/followerreads/followerreads_test.go:1227 +0xf18
testing.tRunner(0x4014282000, 0x400eb78030)
GOROOT/src/testing/testing.go:1934 +0xc8
created by testing.(*T).Run in goroutine 24539
GOROOT/src/testing/testing.go:1997 +0x364
=== RUN TestSecondaryTenantFollowerReadsRouting/latency-based
--- FAIL: TestSecondaryTenantFollowerReadsRouting/latency-based (3.55s)
```
Help

See also: [How To Investigate a Go Test Failure \(internal\)](https://cockroachlabs.atlassian.net/l/c/HgfXfJgM)

/cc @cockroachlabs/unowned

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Jira issue: CRDB-66929