Disable TestPowershellUTF8EncodingStdin powershell
What does this MR do?
Disabled the TestPowershellUTF8EncodingStdin/powershell test. Keeps the /pwsh variant.
Why was this MR needed?
This existing failure is now being checked (!3846 (merged)) and it's blocking unrelated changes in the pipeline.
What's the best way to test this MR?
Run TestPowershellUTF8EncodingStdin and powershell should not be included.