Enable back presence feature on matrix.org server

[MurzNN]

Regarding to this issue closing comment #3971 (comment), most of presence high load problems are solved now, so maybe there is a good time to turn it on back on matrix.org server?

Because there is a lot of embarrassing questions from users where is a presence feature on Matrix protocol and why it is disabled on "main" matrix.org server...

[anoadragon453]

There's still some outstanding performance work for presence which we'd like to see finished before enabling the feature of matrix.org. Namely those mentioned in #9478.

I would recommend following that bug for progress.

That being said, we do run the feature for another homeserver with around ~100 users internally with no issues.