[BLD] Update Dockerfile cache mounts to address collisions

[eculver]

Description of changes

This updates the caching directives in our rust Dockerfiles to hopefully address the cache contention issues we've been seeing between rust's build cache and Buildkit's native caching machinery. This is as advised from the folks at Depot.

Test plan

tilt up

• Tests pass locally with pytest for python, yarn test for js, cargo test for rust

[github-actions]

Reviewer Checklist

Please leverage this checklist to ensure your code review is thorough before approving

Testing, Bugs, Errors, Logs, Documentation

• Can you think of any use case in which the code does not behave as intended? Have they been tested?
• Can you think of any inputs or external events that could break the code? Is user input validated and safe? Have they been tested?
• If appropriate, are there adequate property based tests?
• If appropriate, are there adequate unit tests?
• Should any logging, debugging, tracing information be added or removed?
• Are error messages user-friendly?
• Have all documentation changes needed been made?
• Have all non-obvious changes been commented?

System Compatibility

• Are there any potential impacts on other parts of the system or backward compatibility?
• Does this change intersect with any items on our roadmap, and if so, is there a plan for fitting them together?

Quality

• Is this code of a unexpectedly high quality (Readability, Modularity, Intuitiveness)

[codetheweb]

I don't think this is viable without further changes because it makes incremental local builds extremely slow. Every file change will cause every service to recompile all dependencies from scratch (try running tilt up, then add a comment to a random Rust file).

[eculver]

I don't think this is viable without further changes because it makes incremental local builds extremely slow. Every file change will cause every service to recompile all dependencies from scratch (try running tilt up, then add a comment to a random Rust file).

Yeah, I was wondering why running tilt up was sooooooo slooowwwww.