Remove lock for internal isGetTasksAllowed

The method only checks recents and permission. The former is a field
which won't change since boot. The latter doesn't involve any WM
stuffs. Other places also use it without lock.

This avoids unnecessary lock contention when calling ActivityManager#
getRunningAppProcesses, getProcessMemoryInfo, getRunningServices.

Bug: 204870457
Test: Test: CtsWindowManagerDeviceTestCases
Change-Id: Ie1f1d1f58543cf25197f42caa01565039ced4b32

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

@@ -5488,10 +5488,8 @@ public class ActivityTaskManagerService extends IActivityTaskManager.Stub {
 
         @Override
         public boolean isGetTasksAllowed(String caller, int callingPid, int callingUid) {
-            synchronized (mGlobalLock) {
-                return ActivityTaskManagerService.this.isGetTasksAllowed(
-                        caller, callingPid, callingUid);
-            }
+            return ActivityTaskManagerService.this.isGetTasksAllowed(
+                    caller, callingPid, callingUid);
         }
 
         @HotPath(caller = HotPath.PROCESS_CHANGE)