[libc++] Add UNSUPPORTED annotations to more <format> tests on GCC 12

[libc++] Add UNSUPPORTED annotations to more <format> tests on GCC 12

Those seem to have been failing for a while but we might not have noticed
because of the recent CI instability issues. I'm marking them as unsupported
to try to get the CI functional again, especially since the majority of
<format> tests are already not working on GCC 12.