Fix typo in ANR subject

Test: m && atest
Bug: 300092859
Change-Id: I0078559af4cd73c5beed54c1b6dc18faf5391737
diff --git a/services/core/java/com/android/server/Watchdog.java b/services/core/java/com/android/server/Watchdog.java
index 6baae4b..b536c06 100644
--- a/services/core/java/com/android/server/Watchdog.java
+++ b/services/core/java/com/android/server/Watchdog.java
@@ -323,7 +323,7 @@
         String describeBlockedStateLocked() {
             final String prefix;
             if (mCurrentMonitor == null) {
-                prefix = "Blocked in handler on ";
+                prefix = "Blocked in handler";
             } else {
                 prefix =  "Blocked in monitor " + mCurrentMonitor.getClass().getName();
             }