insights: allow commit indexer to continue if it attempts to record the same commit twice

Created by: chwarwick

The purpose of the commit indexer is to capture all of the commits in a repo and record the time associated with them, when running git log it is inclusive of the before and after times specified and occasional later runs of the indexer will pick up the same commit a 2nd time.

This ignores the error and allows indexing to continue if an attempt is made to insert a commit that has the same time, hash and repo as a commit that was already indexed.

resolves #34576 (closed)

Test plan

Added automated tests, all tests pass