insights: aggregation drill down should clear grouping selection

Created by: chwarwick

Currently when clicking a bar in the aggregation to drill into the results the current aggregation mode is persisted. This results in an experience that is not optimal because the following can occur based on the grouping type:

• Repo/File/Author - results now have 1 repo/file/author so the aggregation is not useful
• Capture Group
  1. The new search query may no longer have a capture group and show a message the grouping type is not valid for the query.
  2. The original search had a 2nd capture group and is now aggregate. This is good

Clearing the aggregation mode on drill down would provide a better experience in most cases and preserve the desired behavior of the capture group search when the original query had multiple capture groups.

/cc @joelkw @felixfbecker @vovakulikov @unclejustin