bootstat: test error out only on first bad bootloader reason

Hopefully the quick property test is first, setting the stage for
ignoring future failures.  This solves a problem with multiple
test failures directly attributed to a CTS compliance issue
with the bootloader's boot reason.  One test fails, the remainder
get a pass on this one issue.

Test: boot_reason_test.sh
Bug: 63736262
Change-Id: Id56946b6f2f3a33d65bd1830543838f153290759