Temporarily disable FreeBSD-12
Temporarily disable FreeBSD-12

...until the bugs in the google-compute-engine scripts are fixed
upstream.

Change-Id: I0426289b76d4c89a9a40ddd0a2d9ed96415eccb4

bazelbuild/continuous-integration,bazelbuild/continuous-integration,bazelbuild/continuous-integration,bazelbuild/continuous-integration,bazelbuild/continuous-integration,bazelbuild/continuous-integration,bazelbuild/continuous-integration,bazelbuild/continuous-integration