Revert "Revert "[GlobalISel][Localizer] Enable intra-block localization of already-local uses.""

This reverts commit 5583c2f2.

The lldb bot failure was a test that was fragile and sensitive to irrelevant
changes in instruction ordering. Re-committing this as the test should have
been skipped for AArch64 now.

Differential Revision: https://reviews.llvm.org/D75555