When a conference is to happen in a domain which is not the defaut, its config
is loaded and set. As part of this process, lib-jitsi-meet is disposed. Because
disposing is asynchronous, events happen in this sequence:

- set new config
- dispose lib (which effectively wipes the config)
- init lib

This results in the library to be initialized without the loaded config, which
was lost. This commit fixes that by delaying setting the config and
re-initializing the library until it was disposed.