Skip bootstrap APEX RC files for the second round

Reading .rc files from bootstrap APEXes causes "double loading".
This works for services because init just ignores duplicates. But it
emits error logs, which can mislead even though there's no actual
errors. Besides, for actions, duplicates can cause a problem when
commands are not idempotent.

So, when loading RC files from APEXes for the second time, we'd better
skip those bootstrap APEXes.

Bug: 290148081
Test: VendorApexHostTestCases
Change-Id: Ia630dbd14046064b5e5c612c01ebacf57091c8d4