GREP_OPTIONS Color settings cause shell output failure

### Describe the bug.

See context at https://github.com/dotnet/install-scripts/issues/602
We should unset this variable in the command executor or when we call the invoker

### Please attach log file(s) here if you have any.

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### Reproduction Steps

see issue

### Expected Behavior

see issue

### Exceptions & Errors (if any)

_No response_

### .NET Install Tool Version

latest

### Your operating system? Please provide more detail, such as the version and or distro above.

N/A

### VS Code Version

_No response_