infra/gcp/roles: fix regex handling
infra/gcp/roles: fix regex handling

Each permissionRegex is now wrapped in parentheses to become its own
group when passed to grep -E. This ensures ^ and $ characters in each
regex don't end up applying to the whole | concatenation of regexes.

kubernetes/k8s.io,kubernetes/k8s.io,kubernetes/k8s.io,kubernetes/k8s.io