[Backport staging] Make threads disabled by default (#9815)

* Make threads disable by default

* restore e2ee tests

* fix threads e2e spec for beta joining

(cherry picked from commit 134e3d7ae8)

Co-authored-by: Germain <germains@element.io>

src/settings/Settings.tsx

@@ -261,7 +261,7 @@ export const SETTINGS: { [setting: string]: ISetting } = {
         controller: new ThreadBetaController(),
         displayName: _td("Threaded messages"),
         supportedLevels: LEVELS_FEATURE,
-        default: true,
+        default: false,
         betaInfo: {
             title: _td("Threaded messages"),
             caption: () => (