`activate.nu` is not respecting `VIRTUAL_ENV_DISABLE_PROMPT`

[m-lima]

Issue

Other activation scripts monitor the env var VIRTUAL_ENV_DISABLE_PROMPT to decide if the prompt should be changed or not. activate.nu, however, does not do so

Environment

• OS: MacOS 12
• Shell: nushell

Output of the virtual environment creation

The activation itself has no issues and works as expected. It's just the prompt that is unconditionally changed for nushell