Adds STX_MIRROR as environment variable on the build containers and
mount the /workspace/mirrors/starlingx directory into the containers
at /import/mirrors/starlingx during helm provisioning, If directory
does not exists K8s will create an empty directory.
Minikube mounts $STX_BUILD_HOME as /workspace hence why we need
/workspace/<dir> on the yaml files which will mount our local
directories into the containers.
Story: 2008846
Task: 43768
Signed-off-by: Luis Sampaio <luis.sampaio@windriver.com>
Change-Id: I1983ca8868e24bb7b734f122500fcfbc167cc9f7
3cd4bf20c6