ci: Streamline internal gems CI config

.gitlab/ci/rules.gitlab-ci.yml

.gitlab/ci/templates/gem.gitlab-ci.yml

.gitlab/ci/vendored-gems.gitlab-ci.yml

gems/gem.gitlab-ci.yml

vendor/gems/attr_encrypted/.gitlab-ci.yml

vendor/gems/bundler-checksum/.gitlab-ci.yml

vendor/gems/cloud_profiler_agent/.gitlab-ci.yml

vendor/gems/devise-pbkdf2-encryptable/.gitlab-ci.yml

vendor/gems/gitlab_active_record/.gitlab-ci.yml

vendor/gems/ipynbdiff/.gitlab-ci.yml

vendor/gems/mail-smtp_pool/.gitlab-ci.yml

vendor/gems/microsoft_graph_mailer/.gitlab-ci.yml

vendor/gems/omniauth-azure-oauth2/.gitlab-ci.yml

vendor/gems/omniauth-gitlab/.gitlab-ci.yml

vendor/gems/omniauth-salesforce/.gitlab-ci.yml

vendor/gems/omniauth_crowd/.gitlab-ci.yml

vendor/gems/sidekiq-reliable-fetch/.gitlab-ci.yml