Change default rewind time to 10s

This allows the user to better search through an episode, by allowing
them to rewind less than what was just forwarded. It is also aligned
with how other apps out there behave.

Closes: #3262

core/src/main/java/de/danoeh/antennapod/core/preferences/UserPreferences.java

@@ -443,7 +443,7 @@ public class UserPreferences {
     }
 
     public static int getRewindSecs() {
-        return prefs.getInt(PREF_REWIND_SECS, 30);
+        return prefs.getInt(PREF_REWIND_SECS, 10);
     }
 
     public static String[] getAutodownloadSelectedNetworks() {