Clear service variable when onCreate() fails to start foreground service

Co-authored-by: adbenitez <24558636+adbenitez@users.noreply.github.com>

src/main/java/org/thoughtcrime/securesms/service/FetchForegroundService.java

@@ -92,6 +92,9 @@ public final class FetchForegroundService extends Service {
       startForeground(NotificationCenter.ID_FETCH, notification);
     } catch (Exception e) {
       Log.w(TAG, "Failed to start foreground service", e);
+      synchronized (SERVICE_LOCK) {
+        service = null;
+      }
       stopSelf();
       return;
     }