annotation editor api: improve datasource support

[gabor]

when the angular-removal from datasources happened, certain shortcuts had to be added to the code, because the "after angular" annotation API cannot currently support certain datasources, like prometheus, so code like this was added: https://github.com/grafana/grafana/blob/main/public/app/features/annotations/standardAnnotationSupport.ts#L231-L260

the situation should be improved so that such identify-datasource-by-name checks are not needed.

[github-actions]

This issue has been automatically marked as stale because it has not had activity in the last year. It will be closed in 30 days if no further activity occurs. Please feel free to leave a comment if you believe the issue is still relevant. Thank you for your contributions!

[gabor]

(seems thsi never got assigned to a squad, so i assigned it manually to frontend-platform)

[JoaoSilvaGrafana]

Annotations are part of dashboards squad, I have opened a PR to change the codeowners to reflect that and will move this issue to that squad.