Artifacts for GCC 9-14 on 14.1 AArch64, 4-14 on 13.4 x86-64

We were able to build GCC 7 and 8 on FreeBSD 13.2 AArch64, but neither
builds successfully with 14.1. For both 7 and 8, an error about the file
format of `crtn.o` is thrown from `collect2`/`ld`. It's unclear why
that's happening and I'm not sure I care enough to figure it out and fix
it vs. just bumping the minimum GCC version on FreeBSD AArch64 to 9.

Delete most 13.2 artifacts except GCC 7 and 8 for AArch64

Since GCC 9+ built successfully on AArch64, we can "safely" delete the
corresponding 13.2 artifacts. Were we to drop the GCC 7 and 8 artifacts
and require the use of 9+ going forward on 14.1, we would lose support
for libgfortran 4. Since binaries built for 13.2 should in theory work
on 14.1 (though that doesn't seem to always hold in practice), it should
conceivably work to keep around the 13.2 artifacts for GCC 7 and 8. It
is also conceivable that doing so would cause more problems than it
solves in ways that are harder to debug.

For x86-64, we can delete all GCC artifacts, as all versions built
successfully with 13.4.

Author: ararslan