The main wiki server configuration is always used

[oanalavinia]

Steps to reproduce:

1. Have the application installed on 2 wikis: main and a subwiki (e.g. test_wiki)
2. Configure the Collabora server for both wikis, but with different values. For reproducing the issue easily, the main wiki will have a correct address, while the test_wiki will have a dummy value.
3. Try to edit a file on test_wiki

Expected result: it does not work, since a correct server address was not provided
Actual result: it does work

[oanalavinia]

The actual problem is that here when the configuration document reference is created, the current wiki will actually mean the main wiki, since this is used inside a rest endpoint, which is on the main wiki (see step1 -> step2 -> step3)