Add main-repo prefixes
This is required to remain compatible with the default-on Bazel flag
--incompatible_unambiguous_label_stringification.
Test: bp2build.sh CI alongside bazel release to 4e7d2a
Change-Id: I620dbb0822f4e690e896b941478f661457295abe
The code in this directory is experimental. Bazel support for Android Platform is undergoing active development and workflow stability is currently not guaranteed.