Merge develop changes to master

Many changes, most significant is switching from python server to postgrest server.

@wrona Could you add a comment about what this does and how much CPU usage is reduced by the change? Inquiring minds want to know :-)

DB_ROOT_SPEC story started on analysis why hive-staging load is so high, even postgresql didn't take all of it. It appeared that postgREST processes each a lot of CPU when traffic is sent there. Guys found this: https://github.com/PostgREST/postgrest/pull/1794 Because there was no rewriter container, requests were sent to the root and I think it consumed more CPU. @mickiewicz you had some grafana measures where Postgrest CPU impact was recorded.

added 2 commits

• 28f1e4a5 - remove a bunch of unused indexes
• 6dc32f8b - remove references to removed indexes

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added 1 commit

• 73975ab3 - Update list_subscribers to match the previous implementation order regarding joins and conditions

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Closed in favor of !828 (merged)

closed