rm: fix too long filename corner case

[tgrez]

Fixes #8215

[sylvestre]

could you please add a test to make sure we don't regress in the future? thanks

[github-actions]

GNU testsuite comparison:

Skipping an intermittent issue tests/misc/stdbuf (passes in this run but fails in the 'main' branch)
Skipping an intermittent issue tests/timeout/timeout (passes in this run but fails in the 'main' branch)

[tgrez]

A test checking regression added and verified that it fails without the fix (should have started with the test;)

However, AFAICT MacOS and Windows filepaths have length limits (1024 and 260 respectively) and the tests still add a /tmp directory, so I limited the test to run only for Linux. Hope it's okay.

[github-actions]

GNU testsuite comparison:

Skip an intermittent issue tests/misc/tee (fails in this run but passes in the 'main' branch)
Skipping an intermittent issue tests/tail/inotify-dir-recreate (passes in this run but fails in the 'main' branch)
Skipping an intermittent issue tests/timeout/timeout (passes in this run but fails in the 'main' branch)

[cakebaker]

Thanks!