* Remove an unused stream ID generator.
* Remove the now unused remote profile cache.

Reducing the amount of state we pull from the DB is useful as fetching state is expensive in terms of DB, CPU and memory.

Avoid breaking a URL preview completely if the chosen image 404s
or is unreachable for some other reason (e.g. DNS).

As opposed to only considering a user to have "participated" if they
replied to the thread.

* Skip `og` and `meta` tags where the value is empty.
* Fallback to the favicon if there are no other images.
* Ignore tags meant for navigation.

* Update worker docs to remove group endpoints.
* Removes an unused parameter to `ApplicationService`.
* Break dependency between media repo and groups.
* Avoid copying `m.room.related_groups` state events during room upgrades.

Currently, we try to pull the event corresponding to a sync token from the database. However, when
we fetch redaction events, we check the target of that redaction (because we aren't allowed to send
redactions to clients without validating them). So, if the sync token points to a redaction of an event
that we don't have, we have a problem.

It turns out we don't really need that event, and can just work with its ID and metadata, which
sidesteps the whole problem.

The remaining piece is a background update that is needed
for backwards compatibility.

* Raise a dedicated `InvalidEventSignatureError` from `_check_sigs_on_pdu`

* Downgrade logging about redactions to DEBUG

this can be very spammy during a room join, and it's not very useful.

* Raise `InvalidEventSignatureError` from `_check_sigs_and_hash`

... and, more importantly, move the logging out to the callers.

* changelog

The replication logic for groups is no longer used, so the message
passing infrastructure can be removed.

Signed-off-by: Sean Quah <seanq@matrix.org>

Signed-off-by: Sean Quah <seanq@matrix.org>

Co-authored-by: Richard van der Hoff <1389908+richvdh@users.noreply.github.com>

While the query was fast, we were calling it *a lot*.

event_edges.room_id is implied by the event id, so there is no need to join on the room id.

Co-authored-by: Richard van der Hoff <1389908+richvdh@users.noreply.github.com>

This reverts commit e0fae823.