Forced Measurement Selection in Data Explorer

**ETA:** _2022-05-15_
**Issue#:** _https://github.com/influxdata/ui/issues/4288)_

Forced Measurement Selection in Data Explorer

An enhancement is being made to the visual query builder inside of data explorer to force the user to make a measurement selection as their first choice after choosing a bucket. This was done to help aid customers who were having performance issues with large datasets because they were sometime choosing a field without first choosing a measurement which caused all measurements, field, and tag metadata to have to be retrieved. This will make sure they are narrowing down their query to a specific measurement.

We need to update our documentation to show the new Measurement selection in the first pane after Bucket selection:_

##### Relevant URLs
- _Provide relevant URLs (issues, community threads, existing doc pages, etc.)_

Start by reviewing the Data Explorer documentation and the linked visual query builder issue, https://github.com/influxdata/ui/issues/4288. Update the relevant page to show Measurement as the first pane after Bucket selection, including the reason this narrows metadata retrieval. Done means the documented flow matches the new UI behavior.

Written by the indexing model from the issue text.