Fix user directory insertion due to missing room_id

Fix user dir to not assume existence of user

Add cache for is_host_joined

Tweak the ranking of PG user dir search

Don't assume existence of events when updating user directory

Throw exception when not retrying when downloading media

Change is_host_joined to use current_state table

Cache state deltas

Fix has_any_entity_changed

Fix removing of pushers when using workers

Mark remote invite rejections as outliers

Occaisonally has_any_entity_changed would throw the error: "Set changed
size during iteration" when taking the max of the `sorteddict`. While
its uncertain how that happens, its quite inefficient to iterate over
the entire dict anyway so we change to using the more traditional
`bisect_*` functions.

This bypasses a bug where using the state groups to figure out if a host
is in a room sometimes errors if the servers isn't in the room. (For
example when the server rejected an invite to a remote room)

Ensure we don't use unpersisted state group as prev group

Fix bug where state_group tables got corrupted

This is due to the fact that we prefilled caches using txn.call_after,
which always gets called including on error.

We fix this by making txn.call_after only fire when a transaction
completes successfully, which is what we want most of the time anyway.

Don't start user_directory handling on workers

Faster cache for get_joined_hosts

Split up device_lists_outbound_pokes table for faster updates.