Suggests to use a JSON structured log instead

Related to https://gitlab.com/gitlab-org/gitlab-ce/issues/54102

Enables frozen string for the following files:

* lib/generators/**/*.rb
* lib/gitaly/**/*.rb
* lib/google_api/**/*.rb
* lib/haml_lint/**/*.rb
* lib/json_web_token/**/*.rb
* lib/mattermost/**/*.rb
* lib/microsoft_teams/**/*.rb
* lib/object_storage/**/*.rb
* lib/omni_auth/**/*.rb
* lib/peek/**/*.rb
* lib/rouge/**/*.rb
* lib/rspec_flaky/**/*.rb
* lib/system_check/**/*.rb

Partially addresses #47424.

Closes #42342

Server Side Request Forgery in Services and Web Hooks

See merge request gitlab/gitlabhq!2337