Revert "Add partial bp2build support for APEX targets."

Revert submission 1733232-roboleaf-apex

Reason for revert: b/192523357 Broken build 7512065 on aosp-master on sdk_x86_64-sdk
Reverted Changes:
Ie82c263f6:Add a stub rule for building APEX bundles.
I93e2a25fa:Add partial bp2build support for APEX targets.

Change-Id: I8e836fe7f466e02f3108680f9653412299e929e0