Make android.test.mock use api_srcs instead of jarjar

Since the jarjar solution was introduced, api_srcs support was
added back to java_sdk_library. Migrate to that.

Aside from the slightly simpler setup, I also noticed the jarjar-version
left some *.uau and *.xml files in the output jar.

Test: diff jar before and after
Change-Id: I9724cce159ea4f1b882505f589a9cfe17a880514