Disable a couple of errorshow tests on FreeBSD (#30428)
These two specific errorshow tests work on FreeBSD debug builds, like
what we run on CI, but they fail with regular FreeBSD builds. The
buildbots that upload nightly binaries ensure that the tests pass prior
to uploading, and the fact that this doesn't pass on regular builds is
what's keeping us from having FreeBSD nightly binaries.
See issue 30233.
