Indicate whether the alert is firing

What does this MR do?

Alert on the metrics dashboard indicates that it is firing (displays in red badge), shows tooltip in case of multiple alerts.

⚠ Currently we do not support setting up multiple alerts, though it is planned to be implemented in the nearest future. So without mock data you'll be able to check only scenarios with single alert

Screenshots

Non-firing alerts

single	multiple

Firing alerts

single	multiple

Steps to reproduce

1. Setup cluster with prometheus integration: https://gitlab.com/gitlab-org/gitlab-development-kit/-/blob/master/doc/howto/prometheus.md
2. Navigate to Operations->Metrics
3. Add metrics alert (⚠ only single alert can be setup)

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers
• Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• Security reports checked/validated by a reviewer from the AppSec team

References #208496 (closed)