Streams tables are never cleared out

[matrixbot]

This issue has been migrated from #5888.

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A number of 'stream' tables are appended-to, but are never cleared out. Such tables include:

• cache_invalidation_stream_by_instance (fixed by Remove old rows from the cache_invalidation_stream_by_instance table automatically. (This table is not used when Synapse is configured to use SQLite.) matrix-org/synapse#15868)
• current_state_delta_stream
• presence_stream (does get cleaned out; has been ever since its creation in Rewrite presence for performance. matrix-org/synapse#582)
• device_inbox (not really a 'stream' table actually, so a separate problem: device_inbox never gets emptied #3599)
• device_federation_outbox
• local_group_updates (removed in Drop tables used for groups/communities. matrix-org/synapse#12967)
• push_rules_stream
• ex_outlier_stream
• public_room_list_stream (now removed)
• device_lists_changes_in_room (probably not really a stream table, Clear out device_lists_changes_in_room table periodically. #13043)

[richvdh]

Personally, I'd like us to refactor the replication streams so that we don't need these tables in the first place: #13456

[dawagner]

I'm managing a matrix server whose push_rules_stream table weighed 16GB 2 months ago and is now 24GB. I suspect it shouldn't be that large but I couldn't find how to purge the obsolete entries. Is there some way to do so?