Remove unused LXSS_DISTRO_FLAGS_WSLCORE_MODE

[OneBlue]

Summary of the Pull Request

PR Checklist

• Closes: Link to issue #xxx
• 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 PR removes the unused LXSS_DISTRO_FLAGS_WSLCORE_MODE flag and its associated code path from the WSL service. The flag was previously defined but no longer serves a purpose in the codebase.

Key Changes

• Removed LXSS_DISTRO_FLAGS_WSLCORE_MODE constant definition
• Updated LXSS_DISTRO_FLAGS_ALL to exclude the removed flag
• Removed the early return logic in WslCoreInstance::Initialize() that checked for this flag

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
src/windows/service/inc/wslservice.idl	Removed flag definition and updated aggregate flag constant
src/windows/service/exe/WslCoreInstance.cpp	Removed conditional early return that checked for the unused flag