[CI/Build] fix uv caching in Dockerfile

[dtrifiro]

uv uses its own cache in /root/.cache/uv and does not use /root/.cache/pip

fixup to #13566

[github-actions]

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[mgoin]

Thanks, this was an oversight

[dtrifiro]

Force pushed to add dco signoff, unsure why CI is failing though.

[dtrifiro]

Something wrong with CI, unrelated to this change?

[2025-02-20T15:37:47Z] 🚨 Error: Error setting up job executor: The global environment hook exited with status 53

[DarkLight1337]

Let me try rebuilding.

Update: The Docker container has been built successfully so I'm merging this now.