Remove duplicate compact settings, handle device level updates

This removes the duplicate setting for compact layout from the appearance tab,
and leaves the "advanced" one, matching the intention from Design.

This also adds the relevant handling to ensure the device-level setting triggers
an update immediately when changed.

Fixes https://github.com/vector-im/riot-web/issues/14304

src/settings/Settings.js

@@ -202,7 +202,7 @@ export const SETTINGS = {
         default: false,
     },
     "useCompactLayout": {
-        supportedLevels: LEVELS_ACCOUNT_SETTINGS,
+        supportedLevels: LEVELS_DEVICE_ONLY_SETTINGS,
         displayName: _td('Use a more compact ‘Modern’ layout'),
         default: false,
     },