Deprecate checkNotNull in favor of Objects.requireNonNull().

Remove one of unused overloads. The same change passed on master:
ag/10013392

Bug: 126528330

Test: Treehugger
Test: made equivalent change in internal branch to verify that removed method is not in use

Change-Id: I37c5b93e2ffbfa38a5b9feb4cae2062ef24acec5