test_install.rs: strip myself instead of strip_source_file

[oech3]

Closes #13682
Closes #13664
Closes #13612

[github-actions]

GNU testsuite comparison:

GNU test failed: tests/cp/parent-perm-race. tests/cp/parent-perm-race is passing on 'main'. Maybe you have to rebase?
Skipping an intermittent issue tests/cut/bounded-memory (passes in this run but fails in the 'main' branch)
Note: The gnu test tests/printf/printf-surprise is now being skipped but was previously passing.

[cakebaker]

Thanks!