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
1 file changed