[ENHANCEMENT] Speed up CI pipeline execution

[Zespre Chang]

We leverage GHA's matrix for building both virtbmc-controller and virtbmc container images in the same job template. While it solves #14, it introduces a new issue: duplication. Some of the steps are unnecessary for another run. It just makes the CI waiting time longer.

We need to find out whether there's a good way to solve the issue or abandon the meta-action step and specify our own image tags.