Refactor incident tabs

What does this MR do and why?

Describe in detail what your merge request does and why.

This MR is part of a splitting up of !98505 (closed). There will be some MR's that will build on this.

There are no visual changes, the only HTMl output change is adding a div wrapping timeline and metric tabs but there is no visible difference.

Screenshots or screen recordings

Screenshots are required for UI changes, and strongly recommended for all other merge requests.

before	after

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

To ensure alerts tab is enabled also

1. Ensure you are running enterprise edition
2. Go to a project's settings, then Monitor
3. Expand Alerts
4. Add a new integration, HTTP endpoint is fine, give a mock name, in customise alert you can paste { "events": [{ "application": "Name of application" }] }
5. Click "save and create test alert
6. Navigate to Monitor -> Alerts
7. Open the new test alert 7.a (If it isn't there, you can navigate back to integration settings, open the settings for the new integration, go to the tab called "send test alert" and paste this { "events": [{ "application": "Name of application" }] } and send
8. in the Alert click "create incident on the top right of the alert page

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #367856