Prevent materialized view refreshes from clobbering each other

[bellerbrock]

Expected Behavior

Instead of using the 'currently_refreshing' column in the matviews table before issuing a new refresh, check if one is running via pg_stat_activity. If one is and it is of the same type, terminate it and then issue a new refresh.

For Bugs:

Environment

Steps to Reproduce

[bellerbrock]

partially completed here, need to test and finish https://github.com/solgenomics/sgn/tree/topic/fix_clobbering_matview_refresh

[lukasmueller]

what is the status of this ticket? I think it can probably be closed?

[lukasmueller]

We should probably close this ticket at this point if it is not considered a problem anymore...?