`${env:<VARIABLE>}` substitution is no longer working for `.env` files

[karrtikr]

We document it so it should work: https://code.visualstudio.com/docs/python/environments#_variable-substitution

[luabud]

Dupe of microsoft/vscode-python-debugger#523?

[luabud]

in any case, I'm removing the support from the docs until we fix this :)

[karrtikr]

Dupe of microsoft/vscode-python-debugger#523?

Actually that issue is only for debugger, the issue is sometimes ${env: is needed and sometimes its not. So i think we should keep both open.

[eleanorjboyd]

@paulacamargo25 is this still relevant?