Collabora breaks without setting `OC_EVENTS_ENDPOINT`

[JammingBen]

Describe the bug

Using external apps like Collabora without setting OC_EVENTS_ENDPOINT seems to break completely on current main. I guess this was introduced by #2862. This is bad because it's introducing a breaking change.

Steps to reproduce

1. Start a dev stack with collabora, e.g. in our opencloud-compose setup without having OC_EVENTS_ENDPOINT set (basically undo https://github.com/opencloud-eu/opencloud-compose/pull/307/changes)
2. Access web in the browser and open a odt file

Expected behavior

The file opens. Collaboration events like for the mention feature don't work, but they shouldn't affect Collabora as a whole.

Actual behavior

Collabora doesn't start.

[rhafer]

This is not a blocker for the 7.2.0 stable release (as the affected code is not part of it), but should be a blocker for the upcoming rolling release.

[kulmann]

For the next rolling release from main, this means that it must be either 8.0.0 and prominent accouncement of the new required config, OR absent config must only cause a warning in the logs, not a failure.

[micbar]

Let us go with graceful behavior when the variable is missing.

The problem only occurs, when the collaboration service is in a separate container.

We want to switch that in the compose project.

[kulmann]

@fschade could you please implement the change for a graceful behaviour?

[fschade]

@kulmann should we introduce a feature flag, or just skip the initialization (and events) if OC_EVENTS_ENDPOINT is unset?

[kulmann]

@kulmann should we introduce a feature flag, or just skip the initialization (and events) if OC_EVENTS_ENDPOINT is unset?

Just skip the init and events if OC_EVENTS_ENDPOINT is unset. No capability whatsoever required.