Log resultIfPiSenderAllowsBal

In cases where BAL is blocked (or would be blocked if the target SDK
is bumped) it can be helpful to know for what reason it would be allowed
based on the real callers privileges.

Test: atest BackgroundActivityLaunchTest
Change-Id: I1d2dc449bfaddb97661bcb238b19040a58a31d4d

services/core/java/com/android/server/wm/BackgroundActivityStartController.java

@@ -509,6 +509,7 @@ public class BackgroundActivityStartController {
                 + "; intent: " + intent
                 + "; callerApp: " + callerApp
                 + "; inVisibleTask: " + (callerApp != null && callerApp.hasActivityInVisibleTask())
+                + "; resultIfPiSenderAllowsBal: " + balCodeToString(resultIfPiSenderAllowsBal)
                 + "]";
         if (resultIfPiSenderAllowsBal != BAL_BLOCK) {
             // We should have returned before if !logVerdictChangeByPiDefaultChange