Cleanup of api settings.md doc

What does this MR do?

The CE api settings.md Doc needed a cleanup, due to missing settings, old settings not removed, bad layout, etc. Discussed in issue https://gitlab.com/gitlab-org/gitlab-ce/issues/49155. WIP until some extra details are verified. This MR is split off from https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/20571 (if you want to see some of the previous commits that are squashed here), to separate docs changes from code changes.

EE Updates are found in https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/6600.

In CE api settings.md:

• Alphabetizes the list.
• Fixes table spacing for readability
• Fixes typo in shared_runners_enabled (true -> boolean)
• Corrects description of clientside_sentry_dsn
• Moved table out of the middle of the Change application settings section, and placed in new section at end.
• Adds Missing Settings:
  • allow_local_requests_from_hooks_and_services - Description from _outbound.html.haml
  • authorized_keys_enabled - Description from _performance.html.haml
  • auto_devops_domain - Description from _ci_cd.html.haml
  • auto_devops_enabled - Description from _ci_cd.html.haml
  • domain_blacklist_raw - Checking
  • domain_whitelist_raw - Checking
  • gitaly_timeout_default
  • gitaly_timeout_fast
  • gitaly_timeout_medium
  • hashed_storage_enabled - Description from _repository_storage.html.haml
  • help_page_text
  • hide_third_party_offers - Description from _third_party_offers.html.haml
  • mirror_available - Description from _repository_mirrors_form.html.haml
  • pages_domain_verification_enabled - Description from _pages.html.haml
  • Add Throttling Settings. Descriptions from _ip_limits.html.haml
    • throttle_authenticated_api_enabled
    • throttle_authenticated_api_period_in_seconds
    • throttle_authenticated_api_requests_per_period
    • throttle_authenticated_web_enabled
    • throttle_authenticated_web_period_in_seconds
    • throttle_authenticated_web_requests_per_period
    • throttle_unauthenticated_enabled
    • throttle_unauthenticated_period_in_seconds
    • throttle_unauthenticated_requests_per_period
• Remove Deprecated Settings? Keep!
  • password_authentication_enabled
  • signin_enabled - Check
  • performance_bar_allowed_group_path
  • performance_bar_enabled
• Changes required to yes for:
  • akismet_api_key
  • clientside_sentry_dsn
  • housekeeping_bitmaps_enabled
  • housekeeping_full_repack_period
  • housekeeping_gc_period
  • housekeeping_incremental_repack_period
  • metrics_port
  • two_factor_grace_period
  • shared_runners_text

Need to check:

• Is performance_bar_allowed_group_id deprecated and so needs to be removed from schema.rb? Nope

• Are settings required based on settings.rb?

• Settings in schema.rb but not found in normal application settings locations

  • after_sign_up_text_html - Markdown cache column (https://gitlab.com/gitlab-org/gitlab-ce/commit/e94cd6fdfe43d9128d37a539cf84f4388c5cf970)
  • cached_markdown_version - Not api accessible, I think.
  • created_at - Ignore
  • health_check_access_token - Not api accessible, I think.
  • help_page_text_html - Markdown cache column (https://gitlab.com/gitlab-org/gitlab-ce/commit/e94cd6fdfe43d9128d37a539cf84f4388c5cf970)
  • runners_registration_token - Not api accessible, I think.
  • shared_runners_text_html - Markdown cache column (https://gitlab.com/gitlab-org/gitlab-ce/commit/e94cd6fdfe43d9128d37a539cf84f4388c5cf970)
  • sign_in_text_html - Markdown cache column (https://gitlab.com/gitlab-org/gitlab-ce/commit/e94cd6fdfe43d9128d37a539cf84f4388c5cf970)
  • updated_at - Ignore
  • uuid - Ignore

Related issues

https://gitlab.com/gitlab-org/gitlab-ce/issues/49155