Remove errorprone's copy of javac

It's no longer used now that errorprone is an annotation processor.
https://github.com/google/error-prone/commit/8627920c7dc14c42462ca0dc7c2bb3357f0e8477

Bug: 253827323
Test: m RUN_ERROR_PRONE=true metalava
Change-Id: Ie630b322b61c8fcfea2cc0c091da62d5ee3a8f47
12 files changed