[llvm] [llvm-lit] Resolve env subcommand required error (PR #98414)

[James Henderson via llvm-commits]

https://github.com/jh7370 commented:

What's the purpose of doing `not --crash env`? That sounds to me like you're trying to show that the internal lit `env` doesn't crash?

Assuming it is needed, shouldn't there be a test for this?

https://github.com/llvm/llvm-project/pull/98414