ignore fast sender clock

Closes #5577
// FREEBIE

src/org/thoughtcrime/securesms/database/model/MessageRecord.java

@@ -128,8 +128,10 @@ public abstract class MessageRecord extends DisplayRecord {
   }
 
   public long getTimestamp() {
-    if (isPush()) return getDateSent();
-    else          return getDateReceived();
+    if (isPush() && getDateSent() < getDateReceived()) {
+      return getDateSent();
+    }
+    return getDateReceived();
   }
 
   public boolean isForcedSms() {