`bazel run --collect_coverage //some:test` doesn't generate required `collect_coverage` script

### Description of the bug:

When you use `bazel run` on a test target, along with `--collect_coverage`, the required `collect_coverage` script isn't generated even though it's used. It seems like it's not properly added as a run file.

### Which category does this issue belong to?

Core

### What's the simplest, easiest way to reproduce this bug? Please provide a minimal example if possible.

```
$ bazel clean
$ bazel run --collect_coverage //some:test
exec ${PAGER:-/usr/bin/less} "$0" || exit 1
Executing tests from //some:test
-----------------------------------------------------------------------------
external/bazel_tools/tools/test/test-setup.sh: line 339: bazel-out/darwin_arm64-opt-exec-ST-e0b77ff00d50/bin/external/bazel_tools/tools/test/collect_coverage: No such file or directory
```

### Which operating system are you running Bazel on?

macOS 26.3

### What is the output of `bazel info release`?

release 8.5.1

### If `bazel info release` returns `development version` or `(@non-git)`, tell us how you built Bazel.

_No response_

### What's the output of `git remote get-url origin; git rev-parse HEAD` ?

```text

```

### If this is a regression, please try to identify the Bazel commit where the bug was introduced with bazelisk --bisect.

_No response_

### Have you found anything relevant by searching the web?

_No response_

### Any other information, logs, or outputs that you want to share?

_No response_

Start by reproducing the command `bazel run --collect_coverage //some:test` and inspect `external/bazel_tools/tools/test/test-setup.sh` around line 339, where the missing script is used. Trace how the `collect_coverage` script is added to run files, then verify that the command completes without the reported missing-file error.

Written by the indexing model from the issue text.