[Lens] Remove dynamic names in telemetry collection

[wylieconlon]

There is some data that the Lens telemetry is currently collecting which can only be analyzed with scripted fields, due to its use of generated names. Because this data isn't useful for analysis today, we should remove it. There are two metrics that would be affected by this:

stack_stats.kibana.plugins.lens.events_90_days.indexpattern_dimension_operation_from_{function}_to_{function}
stack_stats.kibana.plugins.lens.suggestion_events_90_days.position_0_of_1

Together, these have generated about 45 separate names because of all the combinations of functions and positions for suggestions. I recommend that we remove both events from collection, as they don't appear to be used.

cc @AlonaNadler @timroes

[elasticmachine]

Pinging @elastic/kibana-app (Team:KibanaApp)