Python Extension and Python Environment Extension both activate when `python.useEnvironmentsExtension` defaults to false

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## Environment data

## Repro Steps

* Install the Python extension
* Install the Python environment extension
* Set the user configuration to:

```json
"workbench.enableExperiments": false,
"python.experiments.enabled": false
```

Reload the window

## Expected behavior

* The Python and Python environment extension agree on which extension is responsible for managing environments

## Actual behavior

* Both extensions activate
* I see two Python selectors
* The `Select Python Environment` selector from the Python Environment extension is missing

## Additional context

The Python Environment Extension uses `inspect` to decide whether `useEnvironmentsExtension` is set to false, but this does not take into account a default value.

The `when` condition of the Command Palette entry uses `when`, which takes default values into account

The Python Extension uses `get`, which takes default values into account

This came up in https://github.com/astral-sh/ty-vscode/issues/551 because it's now unclear which extension ty should consider as being authoritative when it comes to selecting an environment.

Inizia individuando la logica di ispezione della configurazione e di attivazione di Python Environment Extension, quindi confrontala con il comportamento get consapevole dei valori predefiniti di Python Extension e con la when condition di Command Palette. Riproduci il problema con entrambe le estensioni installate e gli esperimenti disabilitati; il lavoro è completato quando le estensioni concordano sulla proprietà dell’ambiente e viene mostrato solo il selettore previsto.

Scritto dal modello di indicizzazione a partire dal testo della issue.