Stop merging in annotations from ojluni-annotated-sdk-stubs

The annotations are already merged into the stubs that are exported
from libcore so this is unnecessary.

Bug: 142113521
Test: m checkbuild
      test this change does not change offline-sdk-docs
Change-Id: Icb0b61f80c91f96eaa22a7f1b92ffdf1825636c8