Remove StorageManagerServiceTest

1)StorageManagerServiceTest fails with initialization error because there is no
  testcase written
2)If we written some testcases, we can't initialize StorageManagerService because
  unable set the "sys.isolated_storage_snapshot" due to selinux violation

Bug: 147206194
Test: atest FrameworksServicesTests:com.android.server.StorageManagerServiceTest

Change-Id: Ie35e73ed1bb9b8cd6e5dbb50520484b01b7b7254
Signed-off-by: Naga Venkata Durga Ashok Mutyala <quic_nmutya@quicinc.com>