init: fix subcontext tests running as non-root.

A recently added subcontext test was failing beause it was running as
non-root, but GTEST_SKIP() didn't work as I expected it to.

In retrospect, all of these tests except for the property one, can
easily run as root, so this changes allows all of these tests to run
as root, while fixing the original issue.

Bug: 144707143
Test: root and nonroot subcontext unit tests
Change-Id: Ia835597701698f6be2101f92d6f4c9450bd3c7dd