Using label as id for py targets

[linzhp]

PR Checklist

Please check if your PR fulfills the following requirements:

• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

• Bugfix
• Feature (please, look at the "Scope of the project" section in the README.md file)
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Documentation content changes
• Other... Please describe:

What is the current behavior?

Gazelle plugin generates a UUID for each py_library target for py_binary and py_test in the same package to refer to. However, creating another identifier such as UUID is not necessary because Bazel already has id for each target, which is its label.

Furthermore, in some large monorepos where it's too slow for Gazelle to index the whole repo, we turn off the indexing with bazel run //:gazelle -- -index=false and rely on CrossResolver to resolve dependencies based on paths conventions. The UUID makes it impossible to resolve dependencies without indexing the whole repository.

What is the new behavior?

Reuse Bazel label as the id for the library and avoid depending on the UUID library. Now CrossResolvers can easily resolve same-package dependencies

Does this PR introduce a breaking change?

• Yes
• No

Other information

If this approach is acceptable, I can create a follow up PR to rename variables to reflect the fact that we are no longer using UUID

[f0rmiga]

Does go mod tidy prune the uuid dependency?

[f0rmiga]

Thanks for addressing my comments.