Prevent re-adding call disconnected before block check completes.

If call filtering completes AFTER a call is disconnected, it is possible
for the call to be re-added to telecom, which is not correct.

Bug: 31083479
Change-Id: I2053d1c7ea17fa634028bf3e118139f3ca342815
diff --git a/src/com/android/server/telecom/CallsManager.java b/src/com/android/server/telecom/CallsManager.java
index d70daec..cc69ca9 100644
--- a/src/com/android/server/telecom/CallsManager.java
+++ b/src/com/android/server/telecom/CallsManager.java
@@ -375,6 +375,7 @@
                     result.shouldAllowCall ? "successful incoming call" : "blocking call");
         } else {
             Log.i(this, "onCallFilteringCompleted: call already disconnected.");
+            return;
         }
 
         if (result.shouldAllowCall) {