Disable non-reboot tests

This change fixes a build issue that was resulting in the TestActivity
being unavailable at runtime and removes the non-reboot variants of
SdCardEjectionTests until we can find a better way to detect when the
APKs on the SD card are no longer available.

Test: atest SdCardEjectionTests
Fixes: 274719632
Bug: 275403538
Change-Id: I88bd67ba5bd8ae6e4008072a5e98d1ad67085c74