run-build-script-ci: add CI test on sdbusplus

run-unit-test-docker.sh is currently untested when making changes
to this repository.  Add a simple CI test that clones sdbusplus
and runs unit tests against it.

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I8425306739b34d03076ffe4f466d38ea235223e4
1 file changed