Take the Threads Activity Centre out of labs (#12439)

* Take the TAC out of labs!

Requires https://github.com/matrix-org/matrix-react-sdk/pull/12438
and ideally https://github.com/matrix-org/matrix-react-sdk/pull/12418

* i18n

* Add test method

That's needed now we we don't include threads in the notif count in the tests

* One less labs setting

* Update snapshot

* Disable release announcement

* Unused import

* Fix some screenshots

* Fix all the unread test cases now room unreads don't include threads

* Fix more tests

* Even more test fixes

* Still more test fixes

* Oh goodness, it's more test fixes

* Fix selectors now there are 2 buttons called Threads

* Disable some tests that aren't passing

for reasons that don't appear releated to any of the TAC work, as
per the comment.

* Remove debugging

* Oops, removed too much

src/settings/Settings.tsx

@@ -1151,15 +1151,6 @@ export const SETTINGS: { [setting: string]: ISetting } = {
         supportedLevels: LEVELS_DEVICE_ONLY_SETTINGS,
         default: [],
     },
-    "threadsActivityCentre": {
-        supportedLevels: LEVELS_ACCOUNT_SETTINGS,
-        labsGroup: LabGroup.Threads,
-        controller: new ReloadOnChangeController(),
-        displayName: _td("labs|threads_activity_centre"),
-        description: () => _t("labs|threads_activity_centre_description", { brand: SdkConfig.get().brand }),
-        default: false,
-        isFeature: true,
-    },
     /**
      * Enable or disable the release announcement feature
      */