Fix "Highlight Groups" for version 2.11.465

There was a slight change in WA 2.11.465, as group tags now end with "@g.us_156_6.0", so now we just hope the "@g.us" is contained in the tag.
This pull request also tries to query the conversationRows map a little less (as it is somewhat performance critical).
Your optimisation is a great point. Can we save yet another one here - and just check if `conversationRow == null` to save this lookup?