Determine why docker-related actions run on schedule

[mrhardman]

Actions such as https://github.com/UKAEA-Edge-Code/hermes-3/actions/runs/26738630817 associated with the original (not VANTAGE) docker image for Hermes-3 appear to run on a schedule, and fail. We should stop this unless it is intentional and beneficial.

@oparry-ukaea @mikekryjak FYI.

[mrhardman]

We still need to merge boutproject/master into the default branch to obtain the fix in boutproject#624.