Re-mark DeviceStateManagerServiceTest#registerCallback as FlakyTest

Seems like this test is still flaky. Let's mark it as
FlakyTest on older branches, and resolve this in the
internal git-main branch going forward.

Bug: 297949293
Bug: 223153452

Test: Presubmit
Change-Id: I81ad9723aa98b4a7fcce287b6a513f03b42f9d53
diff --git a/services/tests/servicestests/src/com/android/server/devicestate/DeviceStateManagerServiceTest.java b/services/tests/servicestests/src/com/android/server/devicestate/DeviceStateManagerServiceTest.java
index 5674101..1c33963 100644
--- a/services/tests/servicestests/src/com/android/server/devicestate/DeviceStateManagerServiceTest.java
+++ b/services/tests/servicestests/src/com/android/server/devicestate/DeviceStateManagerServiceTest.java
@@ -275,6 +275,7 @@
         assertEquals(info.currentState, DEFAULT_DEVICE_STATE.getIdentifier());
     }
 
+    @FlakyTest(bugId = 297949293)
     @Test
     public void registerCallback() throws RemoteException {
         TestDeviceStateManagerCallback callback = new TestDeviceStateManagerCallback();