Use `uv sync` in dockerfiles

[linear]

• Without it, checks executed in GitHub CI won't use the same version as what we use locally.
• This caused DIM-406 (see fix mypy #1167 )
• I've tried previously to just switch to uv sync but there's an issue with the fact that we're also using global python packages. uv sync doesn't work in the global python env, so we probably need to install in a different env, and set up PYTHONPATH to work with both that and global env.