UI Freezes on launch

[manuroe]

We have several reports of some lagginess on the RC TF 0.11.0.
Previous internal TFs were fine. I think #3121 is the culprit. I can see a lot of triggerComputeTrust in the logs.

[manuroe]

[MXCrypto trustLevelSummaryForUserIds] should be async and run on its own queue (or cargoQueue).