Clarify Issuer URL example for GCP OpenID configuration
What does this MR do?
This MR adds trailing slashes to the "Issuer (URL)" examples: https://docs.gitlab.com/ee/ci/cloud_services/google_cloud/#create-a-workload-identity-provider.
In the documentation, we state that "The address must end in a trailing slash" but our examples don't end with it.
Introduced in: !79526 (merged)