Enables frozens string for the following: * lib/gitlab/conflict/**/*.rb * lib/gitlab/cross_project_access/**/*.rb * lib/gitlab/cycle_analytics/**/*.rb * lib/gitlab/data_builder/**/*.rb * lib/gitlab/database/**/*.rb * lib/gitlab/dependency_linker/**/*.rb * lib/gitlab/diff/**/*.rb * lib/gitlab/downtime_check/**/*.rb * lib/gitlab/email/**/*.rb * lib/gitlab/etag_caching/**/*.rb Partially addresses gitlab-org/gitlab-ce#47424.
[10.6] Prevent notes on confidential issues from being sent to chat See merge request gitlab/gitlabhq!2366 # Conflicts: # app/helpers/services_helper.rb
https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/5620#note_13671791