[4.x] Fixed duplicate entry for search queries

[indykoning]

This PR fixes the duplicate entry on search queries in 2 ways.

1. Removing the middleware posting the search query on state change, there is already a listener on insights-event:viewedObjectIDs which does this and also adds the number of hits.
2. Calling firstOrCreate instead of firstOrNew. While this would run an additional query in case the search term does not exist this already deals with UniqueConstraintViolationExceptions, returning the existing model from the database

This way even with bad timing it should not be possible to cause another UniqueConstraintViolationException

[royduin]

We also need this on master?