.well-known/matrix/client should only be loaded once (not twice) on startup

TL:DR https://github.com/element-hq/element-call/pull/2906 means that we might download `.well-known/matrix/client` twice. It should only need to do it once.

In https://github.com/element-hq/element-call/pull/2906 We do a work around to fix that the client does now know about the well known content when we read from it. This has worked at some point in time so sth has changed in the startup order.

It would be great to get to the bottom of this and not do two http request for the well known but only download it once.

Start by reviewing pull request 2906 and tracing the startup path that reads `.well-known/matrix/client`, especially where the client learns the well-known content. Confirm the current sequence causes two HTTP requests, then verify that startup performs only one request while still making the content available to the client.

Written by the indexing model from the issue text.