Don't pass annotation srcs to metalava for modules

Doing so can make these annotation end up in API tracking files
for modules, which we don't want. Put them on the classpath instead.

Bug: 147768409
Test: m
Change-Id: Ibb044c099174ee8591e14b6e2c683a46c1a756ef
Merged-In: Ibb044c099174ee8591e14b6e2c683a46c1a756ef