Revert "Make federation endpoints more tolerant of trailing slashes for some endpoints"

This reverts commit 290552fd.

Improve searching in the userdir

Transfer push rules (notifications) on room upgrade

Improved federation configuration docs.  Specifically detailing  .well-known and SRV based delegation methods. 

Inspiration Valentin Lab <valentin.lab@kalysto.org> for https://github.com/matrix-org/synapse/pull/4781

* Clarify what registration_shared_secret allows for (#2885)

Signed-off-by: Aaron Raimist <aaron@raim.ist>

* Add changelog

Signed-off-by: Aaron Raimist <aaron@raim.ist>

Server side of a solution towards #3622.

Correctly log expected errors when fetching server keys

Disable captcha registration by default in tests

fixes https://github.com/vector-im/riot-web/issues/3155

Make `prev_state` field optional

The `prev_state` field on events is not specced and so synapse shouldn't
explode if an event is missing the field.

Fixes #4787

Implement soft fail