Environment discovery triggers a pop-up warning under macOS Monterey

[brettcannon]

Under macOS Monterey, running the included python2 binary triggers a pop-up warning.

First reported in microsoft/vscode#134635.

[kimadeline]

Verification steps:

• Make sure you are on macOS Monterey, and the system python2 install is still available
• Use VS Code Insiders and download the latest Insiders version of the Python extension
• Run VS Code, activate the Python extension
• Verify that the following warning does not appear: