bp2build: add converted modules to codegen metrics, and remove the

compat layer.

The list of converted modules is used for tracking bp2build progress.

The module_name_to_label aliases weren't really adding much value to
mixed builds, so let's drop the feature for now and simplify the code.

Test: CI
Test: USE_BAZEL_ANALYSIS=1 m droid
Change-Id: I3269344cfe6d1c72c108d66c6e820bc0ec19bb34