runtime: disable TestCrashDumpsAllThreads on openbsd/mips64
runtime: disable TestCrashDumpsAllThreads on openbsd/mips64

This test fails consistently on openbsd/mips64 - disable it until we can investigate
and resolve the issue.

Updates #42464

Change-Id: Ie640f776823137a967a12817ff18953207f558a4
Reviewed-on: https://go-review.googlesource.com/c/go/+/268438
Trust: Joel Sing <4816dabf8db1bc6cac35b3a24cab2ff844b5b0c7@sing.id.au>
Reviewed-by: Cherry Zhang <d62e63aa42ce272d7b6a5055d97e942b33a34679@google.com>

nawawi/go,cloudflare/go,cloudflare/go,nawawi/go,nawawi/go,cloudflare/go,nawawi/go,golang/go,CAFxX/go,CAFxX/go,cloudflare/go,cloudflare/go,cloudflare/go,CAFxX/go,CAFxX/go,golang/go,nawawi/go,nawawi/go,golang/go,CAFxX/go,golang/go,cloudflare/go,CAFxX/go,golang/go,nawawi/go,CAFxX/go,cloudflare/go,golang/go,golang/go,CAFxX/go,golang/go,nawawi/go