Remove the explicit desktop field when creating a Windows process

[OneBlue]

Summary of the Pull Request

This change removes the explicit lpDesktop flag when creating a Windows process.

Windows threads inherit their parent's desktop by default. See: https://learn.microsoft.com/en-us/windows/win32/winstation/thread-connection-to-a-desktop

PR Checklist

• Closes: Link to issue Interop fails for many Windows console programs from WSL in Session 0 without administrative privileges #13909
• Communication: I've discussed this with core contributors already. If work hasn't been agreed, this work might be rejected
• Tests: Added/updated if needed and all pass
• Localization: All end user facing strings can be localized
• Dev docs: Added/updated if needed
• Documentation updated: If checked, please file a pull request on our docs repo and link it here: #xxx

Detailed Description of the Pull Request / Additional comments

Validation Steps Performed

[Copilot]

Pull request overview

This pull request removes the explicit desktop field functionality when creating Windows processes in WSL. The change is based on the principle that Windows threads inherit their parent's desktop by default, making the explicit lpDesktop setting unnecessary. The PR removes the SetDesktop method and its call site, but the implementation is incomplete.

Key changes:

• Removed the SetDesktop(LPCWSTR Desktop) method declaration and implementation from the SubProcess class
• Removed the call to process.SetDesktop(L"winsta0\\default") in the interop process creation flow

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
src/windows/common/interop.cpp	Removes the explicit call to SetDesktop that was setting the desktop to "winsta0\default"
src/windows/common/SubProcess.h	Removes the SetDesktop method declaration from the SubProcess class interface
src/windows/common/SubProcess.cpp	Removes the SetDesktop method implementation

Critical Issue Identified: The refactoring is incomplete. While the SetDesktop method has been removed, the m_desktop member variable (line 58 in SubProcess.h) still exists and is still being used at line 187 in SubProcess.cpp where it assigns to StartupInfo.StartupInfo.lpDesktop. Both the member variable declaration and this assignment need to be removed to properly complete this change.

Comments suppressed due to low confidence (1)

src/windows/common/SubProcess.cpp:98

• The removal of the SetDesktop method is incomplete. The member variable m_desktop (declared at line 58 in SubProcess.h) still exists and is still being used at line 187 in this file (StartupInfo.StartupInfo.lpDesktop = const_cast<LPWSTR>(m_desktop);). Both the member variable declaration and its usage in the Start() method need to be removed to complete this refactoring. Without these changes, lpDesktop will always be set to nullptr (the default value), which may be the intended behavior, but the dead code should be cleaned up.

void SubProcess::SetToken(HANDLE Token)
{
    m_token = Token;
}