Don't require soscmd or p4 for RBTools unit tests.
Review Request #12646 — Created Sept. 26, 2022 and submitted
Our unit tests for SOS and Perforce don't actually invoke
p4, so we don't need to have them installed. This change spies on
check_installto ensure they always show up as installed, preventing
tests from skipping if they're missed.
p4from my path. Verified that unit tests passed.