debug: enable assertions for all tests

This keeps biting us; sanitycheck turns on assertions by
default for tests, but standalone builds, or builds done
for other test infrastructure do not. Put all builds in
the same state.

Specific tests (such as benchmarks) can override this with
CONFIG_FORCE_NO_ASSERT.

Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>