[8.1.0] Use shorthand display form in `Label#debugPrint` (#24855)

This makes the output, which is meant to be friendly to humans, more
concise. If users want `//foo` to be `print`ed as `//foo:foo`, they can
specify `sep = ""` and also print `:foo`, but stripping the name off is
not possible without this change.

Closes #24840.

PiperOrigin-RevId: 713207601
Change-Id: I474fc4eccb1419304368a5c90a22c13b2197b699

Commit
https://github.com/bazelbuild/bazel/commit/e0fada9df1c7fb7ba3c1492ee46aaeba31770bf6



Co-authored-by: Fabian Meumertzheim <fabian@meumertzhe.im>
Co-authored-by: Ian (Hee) Cha <heec@google.com>