Use local docker mirror for test containers

[philwebb]

We might be able to use the local docker mirror that is configured in concourse for test containers. I think we'd need a custom ImageNameSubstitutor and also a custom docker login.

[ttddyy]

@philwebb In my project, I have this implementation for image name substitution, fyi.
(Testcontainers issue comment)

[bsideup]

@philwebb if you configure your mirror like this, it would work out of the box:
https://docs.docker.com/registry/recipes/mirror/

[philwebb]

Trying something on main. If it's stable we can backport.

[wilkinsona]

Backported as part of 429167e for gh-25135.