Improve Global Site Selector

[AndyScherzinger]

• [x] https://github.com/nextcloud/globalsiteselector/issues/53 Failure in user creation in Lookup Server in a Nextcloud Enterprise 22 instance
• [x] https://github.com/nextcloud/globalsiteselector/issues/54 Nextcloud 22: Global Site Selector cannot find the location of a valid user
• ~~https://github.com/nextcloud/globalsiteselector/issues/55 Cross-node share fails if gs.federation is set to its default value~~
• [ ] https://github.com/nextcloud/server/issues/14323 gs.federation does not respect internal

Also notice that the combination of:

• https://github.com/nextcloud/server/issues/29969 and
• https://github.com/nextcloud/globalsiteselector/issues/53

makes Global Scale unusable in some way in the latest major Enterprise versions, 21 and 22.

[pmarini-nc]

https://github.com/nextcloud/globalsiteselector/issues/55 has been closed in favour of https://github.com/nextcloud/server/issues/14323