Feature request: Add more metrics for legend query

### Similar requests

- [X] I have searched and found no existing similar requests

### How are you using Legend?

Legend Query

### What problems are you trying to solve?

Add more metrics for legend query

### Describe the solution you would like to see implemented

- [ ] Add metrics on how users are trying to use query ( account for the workflows we have )
- [ ] Add metrics on users trying to use export to CSV option
- [ ] Users trying to register semi-interactive service from standalone query
- [ ] Metrics around the prefereable query theme by the users
- [ ] No. of times query text mode getting used per session
- [ ] Users prefering constants over variables in query
- [ ] Metrics around percentage of users using hidden panels in query (post filter, functions panel, OLAP, watermark)

### Describe alternatives you have considered

_No response_

### Documentation, Design, Adoption, Migration Strategy

_No response_

### Contribution

- [ ] I would like to work on this feature

The issue does not identify files, tests, or entry points. First clarify which Legend Query workflows and telemetry system are in scope, then define the metrics and acceptance criteria before locating implementation points and tests.

Written by the indexing model from the issue text.