Specify --format for tests to workaround AIX big archive write operation

D122746 missed the following tests, so this patch adds them.

This patch refactors D122949, which marked the following tests XFAIL, but it makes more sense to temporarily add `--format=gnu` option because these tests aren’t testing `llvm-ar` and AIX won’t lose their coverage.

Reviewed By: jhenderson, MaskRay, DiggerLin

Differential Revision: https://reviews.llvm.org/D123063