Remove java_api_contribution modules from .bp files

java_api_contribution modules are dynamically generated from droidstubs
modules or java_sdk_library_import, and is not a user-facing module.
Defining this module is a .bp file is a no-op.

Test: m nothing
Bug: 322242515
Change-Id: I68e450e4c7bbf4a077bfb43cd7e1bbcde4f5a6cc