Fixup shutdown room API

Add option to disable search room lists

Rather than stubbing out the access_log, make it actually log the requests,
which makes it a lot more obvious what is going on during tests.

There are a number of instances where a server or admin may puppet a
user to join/leave rooms, which we don't want to fail if the user has
not consented to the privacy policy. We fix this by adding a check to
test if the requester has an associated access_token, which is used as a
proxy to answer the question of whether the action is being done on
behalf of a real request from the user.

Add option to disable searching in the user dir

Setting this to 50 or so makes a bunch of sytests fail in worker mode.

Rate-limit outgoing read-receipts as per #4730.

Co-Authored-By: erikjohnston <erikj@jki.re>

This disables both local and remote room list searching.

We still populate it, as it can still be accessed via the admin API.

Add note on tuning postgres

Add py27-old test case to buildkite

Use a regular HomeServerConfig object for unit tests