Annotations: Tags not displaying in created annotations if first annotation in range does not have tags

### What happened? If the first annotation doesn't have tags defined, the annotation dataframe passed to the annotations plugin does not have a `tags` field. [First anno has tags](https://play.grafana.org/d/dd37486e-9c2f-43f0-84fb-30d56af8d4ca/wide-time-series?orgId=1&from=2023-05-20T08:45:43.652Z&to=2023-05-20T08:45:52.687Z&timezone=utc) [First anno has no tags, second anno has tags but not displayed](https://play.grafana.org/d/dd37486e-9c2f-43f0-84fb-30d56af8d4ca/wide-time-series?orgId=1&from=2023-05-20T08:44:58.942Z&to=2023-05-20T08:45:58.942Z&timezone=utc) Time range with multiple annotations, first one does not have tags: <img width="890" height="356" alt="Image" src="https://github.com/user-attachments/assets/2b8fa578-dd82-4729-a1d2-7620a7634671" /> After zooming into just one, the tags re-appear: <img width="525" height="508" alt="Image" src="https://github.com/user-attachments/assets/494e5843-c44f-447e-b2b8-616a1a2c3ffb" /> ### What did you expect to happen? Tags should display in any annotation that has them defined. ### Did this work before? Dunno ### How do we reproduce it? Repro on play: [First anno has tags](https://play.grafana.org/d/dd37486e-9c2f-43f0-84fb-30d56af8d4ca/wide-time-series?orgId=1&from=2023-05-20T08:45:43.652Z&to=2023-05-20T08:45:52.687Z&timezone=utc) [First anno has no tags, second anno has tags but not displayed](https://play.grafana.org/d/dd37486e-9c2f-43f0-84fb-30d56af8d4ca/wide-time-series?orgId=1&from=2023-05-20T08:44:58.942Z&to=2023-05-20T08:45:58.942Z&timezone=utc) ### Is the bug inside a dashboard panel? Yes ### Environment (with versions)? N/A ### Grafana platform? None ### Datasource(s)? N/A