Ignore the SyncStorageEngineTest.

The test is incorrectly testing the SyncStorageEngine class - this may
potentially be an issue with how the test module is build. However,
until we get to the root cause, disable this test.

Bug: 401140650
Bug: 405134206
Bug: 404160530
Bug: 402029629
Test: atest SyncStorageEngineTest (ignored)
Flag: EXEMPT bugfix
Change-Id: I9a6b9c6442a37fa86f7ed0f7cdd7f6c0bdb7df56