Add Dockerfile build to PR check workflow

[garrytrinder]

We currently don't test the build of the Dockerfile in the pull request check. As we don't check the build this can lead to not discovering build errors until we release a new version of the docker image to the docker hub. We should include the build step to capture build errors early.

[github-actions]

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[Adam-it]

TBH I don't recall any case in which the building the docker image failed on release workflow when all the builds on all machines passed 🤔.
Although it is a nice improvement I don't think it is that important

[officialasishkumar]

I am working on this in #7230.