[Lens] Omit "over time" suggestion for expensive configurations

[flash1293]

Right now, if there isn't a date histogram in the current datasource configuration, an "over time" suggestion will be made, adding a date histogram aggregation using the default time field.

In some configurations the resulting table is pretty large and rendering the suggestion is freezing the browser for a noticeable amount of time. The suggestion is also not super helpful because the large number of series.

To improve the perceived performance, the "over time" suggestion shouldn't be made if one of the following conditions is true:

• More than one existing bucket dimension
• An existing terms bucket dimension with a size higher than 5

This is not catching all possible cases but should noticeably improve the performance for common configurations.

[elasticmachine]

Pinging @elastic/kibana-vis-editors (Team:VisEditors)