- FederatingHomeserverTestCase: keys last 10x longer
I am guessing that this is the first example of a test which calls
`make_signed_federation_request` after the reactor has advanced by >=
1 second until now.
- Increase max_request_body_size to 4KB in tests
The previous limit prevented the master from accepting some
replication requests which were 1.3kB in size.