Use uv `centralized-project-envs` preview instead of `UV_PROJECT_ENVIRONMENT`

When https://github.com/astral-sh/uv/pull/18214 is released, then we will be able to get uv to store its venvs in its cache directory. This means we should be able to remove the following settings:
https://github.com/DiamondLightSource/python-copier-template/blob/7fa903a148c16baa5e14371ded403f61cc45f8fd/.devcontainer/devcontainer.json#L16-L29

This ticket is to try this out when a new uv is released and available in `ubuntu-devcontainer`

從 .devcontainer/devcontainer.json 開始，尤其檢查第 16-29 行連結的設定，並在所需的 uv 版本可在 ubuntu-devcontainer 中使用後檢查 uv centralized-project-envs preview。移除已過時的設定，並驗證 uv 會將專案虛擬環境儲存在其快取目錄中。

由索引模型根據 Issue 內容生成。