chore: move python integ tests to uv (#1424)

New commands to run python integ tests:

```
# from within integ-tests/python
uv run maturin develop --uv --manifest-path ../../engine/language_client_python/Cargo.toml"
uv run baml-cli generate --from ..
infisical run --env=test -- uv run pytest"
```

References to poetry have been updated to point to uv.

Also delete old github workflows that haven't been relevant for almost a
year.
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----

> [!IMPORTANT]
> Transition Python integration tests from Poetry to uv, update related
scripts and documentation, and remove outdated GitHub workflows.
> 
>   - **Behavior**:
> - Transition Python integration tests from Poetry to uv in
`integ-tests/python`.
> - Update test execution commands in `run_tests.sh` and
`integ-tests/run-tests.sh` to use `uv`.
>     - Remove outdated GitHub workflows related to old testing setups.
>   - **Dependencies**:
> - Update `pyproject.toml` to reflect `uv` usage and remove Poetry
references.
>     - Add `uv.lock` for dependency management.
>   - **Documentation**:
> - Update `README.md` files in `integ-tests` and `integ-tests/python`
to guide using `uv` for setup and testing.
>   - **Misc**:
>     - Remove `tools/install` script as it is no longer relevant.
> 
> <sup>This description was created by </sup>[<img alt="Ellipsis"
src="https://img.shields.io/badge/Ellipsis-blue?color=175173">](https://www.ellipsis.dev?ref=BoundaryML%2Fbaml&utm_source=github&utm_medium=referral)<sup>
for ba4dc61. It will automatically
update as commits are pushed.</sup>


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