Add shortWait to ensure all galelry images are loaded

Signed-off-by: Andy Scherzinger <info@andy-scherzinger.de>

app/src/androidTest/java/com/owncloud/android/ui/fragment/GalleryFragmentIT.kt

@@ -87,6 +87,7 @@ class GalleryFragmentIT : AbstractIT() {
         activity.addFragment(sut)
 
         waitForIdleSync()
+        shortSleep()
         screenshot(activity)
     }