Python feature (os-provided) installation failed if python already installed

[eitsupi]

When I tried to install Python on the rust image, the build failed with an error because it could not create a symbolic link.

#0 48.02 ln: failed to create symbolic link '/usr/bin/python': File exists
#0 48.02 ERROR: Feature "Python" (ghcr.io/devcontainers/features/python) failed to install! Look at the documentation at https://github.com/devcontainers/features/tree/main/src/python for help troubleshooting this error.

My devcontainer.json is this.

{
  "name": "${localWorkspaceFolderBasename}",
  "image": "mcr.microsoft.com/devcontainers/rust:1",
  "runArgs": ["--cap-add=SYS_PTRACE", "--security-opt", "seccomp=unconfined"],

  "customizations": {
    "vscode": {
      "settings": {
        "lldb.executable": "/usr/bin/lldb",
        "files.watcherExclude": {
          "**/target/**": true
        },
        "rust-analyzer.checkOnSave.command": "clippy"
      },
      "extensions": [
        "vadimcn.vscode-lldb",
        "mutantdino.resourcemonitor",
        "rust-lang.rust-analyzer",
        "tamasfe.even-better-toml",
        "serayuzgur.crates"
      ]
    }
  },
  "remoteUser": "vscode",
  "features": {
    "ghcr.io/devcontainers/features/python:1": {}
  }
}

Overwrite the symbolic link, or, I think it is better to stop with an error immediately after executing the script (instead of stopping after some time has passed)

[joshspicer]

This is similar to #212. Maybe of our Features likely need to be tweaked to better handle >1 installation.