Move output validity check from test util to a test case

Since we're running the VM in "beforeClassWithDevice" for CompOS tests,
when the check failed the assertion, it prevents the actual tests to
run. Failing early would be fine, but since we're collecting VM logs in
a test case currently, failing in "beforeClassWithDevice" also hides the
log and makes debugging the VM impossible.

Move the check to CompOsSigningHostTest instead as a new test case. For
CompOsDenialHostTest, removing such a check shouldn't practically cause
any problem.

Bug: 223784827
Test: atest odsign_e2e_test (still pass)
Change-Id: I2e37fd1ee02a04e2d51534ab071b377896ba11ca
2 files changed