Allow launching activities via adoptShellPermission in CTS-in-sandbox tests

For context on CTS-in-sandbox:
 * go/cts-in-sandbox-how, and
 * go/sdk-in-sandbox-activity-support

Flag: TEST_ONLY
Bug: 261864298
Test: atest com.android.server.wm.ActivityStartInterceptorTest && \\
  atest com.android.server.wm.ActivityTaskManagerServiceTests
Change-Id: I4267333eaf8a84871d60635bcdd5bb522f8f96a1