Refactor tracing settings

What does this MR do?

In order to make a new operations settings (Sentry Configuration) easy to add we need streamline some things:

• Use helper method to find or build tracing setting
• Only use the update action
• Create Projects::Operations::UpdateService and inline EE::TracingSettingService
  • Possibly use nested attributes in projects to streamline update
• Extract tracing view into own partial (see https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/8786)
• CE: Create empty settings operations controller
• CE: Create a settings view with render_if_exists for tracing setting

What are the relevant issue numbers?

https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/23724

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• Tests added for this feature/bug
• Tested in all supported browsers
• Conforms to the code review guidelines
• Conforms to the merge request performance guidelines
• Conforms to the style guides
• Conforms to the database guides
• Link to e2e tests MR added if this MR has Requires e2e tests label. See the Test Planning Process.
• EE specific content should be in the top level /ee folder
• For a paid feature, have we considered GitLab.com plans, how it works for groups, and is there a design for promoting it to users who aren't on the correct plan?
• Security reports checked/validated by reviewer