[Feature Flag] Remove `alert_management_minimal` feature flag

What

This issue tracks the removal of the alert_management_minimal feature flag, enabling alert management functionality for the next on-prem release and for all customers using gitlab.com.

This should be removed as soon as all functionality under the 'minimal' epic is complete - &2877 (closed).

Owners

• Team: Monitor:Health
• Most appropriate slack channel to reach out to: #g_monitor_health (and #alert-management-technical-discussion)
• Best individual to reach out to: @tristan.read

Expectations

What are we expecting to happen?

The Alert Management feature will be come available.

• A new route is loaded at /-/alert_management
• Existing users of the Alerts integration will have this functionality activated

What might happen if this goes wrong?

This is a feature under a new route and has minimal interaction with existing features. Any unforeseen issues are unlikely to have a wide impact.

What can we monitor to detect problems with this?

Beta groups/projects

If applicable, any groups/projects that are happy to have this feature turned on early. Some organizations may wish to test big changes they are interested in with a small subset of users ahead of time for example.

• gitlab-org/gitlab project
• gitlab-org/gitlab-com groups
• ...

Roll Out Steps

• Enable on staging
• Test on staging
• Ensure that documentation has been updated - #216243 (closed)
• Enable on GitLab.com for individual groups/projects listed above and verify behaviour
• [n/a] Coordinate a time to enable the flag with #production and #g_delivery on slack.
• [n/a] Announce on the issue an estimated time this will be enabled on GitLab.com
• [n/a] Enable on GitLab.com by running chatops command in #production
• [n/a] Cross post chatops slack command to #support_gitlab-com (more guidance when this is necessary in the dev docs) and in your team channel
• [n/a] Announce on the issue that the flag has been enabled
• Remove feature flag and add changelog entry - !31171 (merged)
• After the flag removal is deployed, clean up the feature flag by running chatops command in #production channel

Tasks before removing flag (aka - this change won't negatively impact GitLab.com)

Complete? ✅/❌	Task	DRI (Directly Responsible Individual)	Additional info / links
✅	Verify security feedback has been actioned	@tristan.read	Question: #216065 (comment 337057535). Original discussion: &2877 (comment 322758974). Issue: #215419 (closed). Resolution: None of the concerns raised in that issue relates to this MR - which only activates the frontend. The backend was live when it was merged - alerts are already stored in the db.
✅	Move detail route behind separate feature flag	@tristan.read	MR: !31175 (merged). Merged.
✅	Test feature end-to-end	@tristan.read	Need to pair with backend
✅	Perform roll-out steps listed above	@tristan.read	MR for flag removal: !31171 (merged)
✅	Show splash page when alert integration disabled	@tristan.read	Issue: #215573 (closed). Proposal: &2877 (comment 337107590). MR here: !31177 (merged). In maintainer review.
✅	Implement permission levels	@syasonik	#216053 (closed)
✅	Complete or disable the status dropdown	@seanarnold	MR: !30576 (merged). Merged.
✅	500 returning from status request	@tristan.read / @syasonik	MR: !31525 (merged)
✅	End to end testing blockers	@tristan.read	#216065 (comment 338753663)

Ready for release (complete before %13.0 is closed)

Complete? ✅/❌	Task	DRI	Additional info / links
✅	Add list view documentation	@oregand	!31225 (merged)
✅	Ensure list view and settings page has UX signoff	@tristan.read	#216065 (comment 337059894)
✅	Verify that the settings page is ready	@tristan.read
✅	Ingestion of prometheus alerts	@ck3g	MR in maintainer review - !30505 (merged)