AAPT2: Update locale script filtering logic

AAPT got an update to its locale script filtering logic that
dealt with enabling the removal of specific locales like
b+sr+Latn. Update AAPT2 to do the same.

Bug: 28055669
Bug: 29412034
Test: aapt2_tests
Change-Id: I3315c0814796cff05dfa1032d66d0306fe2b12bc