.cirrus.yml: do not run golangci-lint for freebsd and mac

Since PR 28760 linting is done for all OSes on linux, so there's no need
to run golangci-lint on Mac and FreeBSD separately. This also fixes the
issue of mixing up golangci-lint caches between different Mac OS X runs.

Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>