[CI] Prevent CI from downloading the `monitoring` image from the internet when it fails to build it

**Is your feature request related to a problem? Please describe.**
See https://github.com/interuss/monitoring/pull/1217#issuecomment-3402732394
This leads to the CI giving unreliable results.

**Describe the solution you'd like**
The CI job to fail when the docker image build fails.
