Revert "Increased short back-off to 16 seconds"

This reverts commit a80a8c66c7.

app/src/main/java/eu/faircode/email/ServiceSynchronize.java

@@ -119,8 +119,8 @@ public class ServiceSynchronize extends ServiceBase implements SharedPreferences
     static final int DEFAULT_POLL_INTERVAL = 0; // minutes
     private static final int OPTIMIZE_KEEP_ALIVE_INTERVAL = 12; // minutes
     private static final int OPTIMIZE_POLL_INTERVAL = 15; // minutes
-    private static final int CONNECT_BACKOFF_START = 16; // seconds
-    private static final int CONNECT_BACKOFF_MAX = 16; // seconds (totally 16+2x20=56 seconds)
+    private static final int CONNECT_BACKOFF_START = 8; // seconds
+    private static final int CONNECT_BACKOFF_MAX = 8; // seconds (totally 8+2x20=48 seconds)
     private static final int CONNECT_BACKOFF_ALARM_START = 15; // minutes
     private static final int CONNECT_BACKOFF_ALARM_MAX = 60; // minutes
     private static final long CONNECT_BACKOFF_GRACE = 2 * 60 * 1000L; // milliseconds