Allowing developer set uv version when building task image

[0yukali0]

Tracking issue

uv --locked problem

Why are the changes needed?

Based on the feedback and tests, this problem is sparked by difference between the one in user side and the one in dockerfile.
My environment:
Ubuntu 24.04
x86_64

Experiment steps.

1. Init a flytekit project(Following the flyte get-started docs)
2. manually add the tensorflow provided in this issue to the pyproject.toml
3. install the uv command with specific version (following the official script )
4. run "uv lock"
5. run "pyflyte run --remote <hello_world.py> <hello_world_wf>" to check the result of building image.

Results are following.

flytekit branch/version	local uv version	docker uv version	frozen flag	pass	error reason
main	0.5.2	0.5.1	None	pass	None
main	0.6.12	0.6.12	None	pass	None
main	0.6.12	0.5.1	None	failed	--locked problem
main	0.6.12	0.5.1	enabled	pass	None

What changes were proposed in this pull request?

How was this patch tested?

building node image with specific uv.

1. install uv
2. uv venv uvsync -p 3.12
3. uv pip install ./flytekit
4. set FLYTE_UV_VERSION
   4.1 export FLYTE_UV_VERSION=0.5.14
   4.2 export FLYTE_UV_VERSION=0.5.2
   4.3 export FLYTE_UV_VERSION=auto which return 0.6.12 returned by sub process result.
5. initialize project (following the get-started doc )
6. manually add the tensorflow requirements mentioned in the issue and run uv lock
7. submit the workflow

Setup process

Screenshots

Check all the applicable boxes

• I updated the documentation accordingly.
• All new and existing tests passed.
• All commits are signed-off.

Related PRs

Docs link

[flyte-bot]

Code Review Agent Run Status

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[flyte-bot]

Code Review Agent Run Status

• Limitations and other issues: ❌ Failure - Bito Automatic Review Skipped - Draft PR
  
  Bito didn't auto-review because this pull request is in draft status.
  To trigger review, mark the PR as ready or type /review in the comment and save.
  You can change draft PR review settings here, or contact the agent instance creator at eduardo@union.ai.

[0yukali0]

This issue is covered by the custome image builder.
Close PR.