[Deployment] Disable ratelimits for @moderator:ubuntu.com

[TheArcaneBrony]

Enhancement Proposal

Draupnir/Mjolnir benefit from having ratelimits disabled. This is especially relevant with the !<prefix> redact command, which is expected to hit ratelimits on sending events (100 messages redacted = 100 new timeline events).
It's probably a good idea to disable ratelimits, in order to ensure the ability to take quick action (eg. high-volume spammers).

[merlijn-sebrechts]

We just had a spammer in the Ubuntu Support room and redacting their messages happened really slowly: multiple minutes for 30-something messages. This is probably slow die to rate limit. Higher rate limit would help us combat spam quicker.

[kewisch]

FWIW rate limiting can be disabled per-user with the admin API at https://matrix-org.github.io/synapse/latest/admin_api/user_admin_api.html#override-ratelimiting-for-users

I had thought we've already taken this step, but let's double check.