Improve FetchPushForegroundService's reliability (#6757)

* Improve `FetchPushForegroundService`'s reliability

- Don't use DI, we can just create the notification channel. This should speed up the creation of the service and reduce the number of `ForegroundServiceDidNotStartInTimeException` received. Also use `MainScope` instead of the app's coroutine scope.
- Move the wakelock releasing mechanism to `onDestroy` so it's always used. Previously, this would only happen when `stopService` was called, which would only happen when `stopSelf()` is called, but not when the OS or the service manager stops the service.

* Add fallback value for the notification channel title

* Replace the wrong string for the notification/channel title

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Co-authored-by: Benoit Marty <benoitm@element.io>

libraries/ui-strings/src/main/res/values/localazy.xml

@@ -199,7 +199,6 @@
   <string name="common_advanced_settings">"Advanced settings"</string>
   <string name="common_an_image">"an image"</string>
   <string name="common_analytics">"Analytics"</string>
-  <string name="common_android_fetching_notifications_title">"Syncing notifications…"</string>
   <string name="common_android_shortcuts_remove_reason_left_room">"You left the room"</string>
   <string name="common_android_shortcuts_remove_reason_session_logged_out">"You were logged out of the session"</string>
   <string name="common_appearance">"Appearance"</string>
@@ -245,6 +244,7 @@ Reason: %1$s."</string>
   <string name="common_failed">"Failed"</string>
   <string name="common_favourite">"Favourite"</string>
   <string name="common_favourited">"Favourited"</string>
+  <string name="common_fetching_notifications_title_android">"Syncing notifications…"</string>
   <string name="common_file">"File"</string>
   <string name="common_file_deleted">"File deleted"</string>
   <string name="common_file_saved">"File saved"</string>