keymaster: Relax testing under GSI

GSI images do not have AVB verification enabled and therefore lack
several properties the keymaster HAL test depended on.  Selectively
disable those parts of the test that would fail with AVB verification
disabled.  Also disable date format checks under GSI.  When invoked from
GSI the TEE-backed keymaster doesn't use the correct date format.

Bug: 130843899
Test: VtsHalKeymasterV4_0TargetTest
Exempt-From-Owner-Approval: change only affects VTS-on-GSI behavior
Change-Id: Idaafb7b515c41290c766a8132f35d498ca15f48a