Query to SystemProperties for BLAST Flag

For some reason DeviceConfig is not successfully querying the
value on crosshatch - move to query SystemProperties directly

Bug: 147096935
Test: build, boot, adb shell device_config put
window_manager_native_boot wm_use_blast_adapter true/false + reboot

Change-Id: Ic09d1b4446f948248e4e58a6a4f3dc336131a5d0

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

@@ -1169,9 +1169,10 @@ public class WindowManagerService extends IWindowManager.Stub
         mAnimator = new WindowAnimator(this);
         mRoot = new RootWindowContainer(this);
 
-        mUseBLAST = DeviceConfig.getBoolean(
+        mUseBLAST = SystemProperties.getBoolean(
+                    String.join(".", "persist.device_config",
                     DeviceConfig.NAMESPACE_WINDOW_MANAGER_NATIVE_BOOT,
-                    WM_USE_BLAST_ADAPTER_FLAG, false);
+                    WM_USE_BLAST_ADAPTER_FLAG), false);
 
         mWindowPlacerLocked = new WindowSurfacePlacer(this);
         mTaskSnapshotController = new TaskSnapshotController(this);