[stable28] fix: override iTip Broker to fix several issues

[backportbot[bot]]

Backport of #48583

Requires: https://github.com/nextcloud/server/pull/49267

Warning, This backport's changes differ from the original and might be incomplete ⚠️

Todo

• [x] Review and resolve any conflicts

• [x] Amend HEAD commit to remove the line stating to skip CI

Learn more about backports at https://docs.nextcloud.com/server/stable/go.php?to=developer-backports.

[kesselb]

Failing tests look related: https://drone.nextcloud.com/nextcloud/server/57857/9/4

[SebastianKrupinski]

Failing tests look related: drone.nextcloud.com/nextcloud/server/57857/9/4

Yeah, I used a reflection trick to test the protected class, which seems to break with php 8.0. Might need to mod the test with a internal class and forward the request to the parent

[kesselb]

Try invokePrivate from tests/lib/TestCase.php

[SebastianKrupinski]

Try invokePrivate from tests/lib/TestCase.php

That worked! Thanks! Wish I knew about that when I created the test originally.