Optimize the WSLA unit tests

[OneBlue]

Summary of the Pull Request

This change updates the WSLA test logic to reuse the same session whenever possible, significantly speeding up the tests

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

[OneBlue]

While testing this, I discovered an uninitialized field in the WSLA_PROCESS_EXITED message, which could incorrectly report that a process was signaled.

Moving forward, let's just always initialize all message fields to prevent this

[Copilot]

Pull request overview

This PR aims to speed up WSLA Windows unit tests by reusing a single default WSLA session across test methods, reducing repeated VM/session initialization overhead.

Changes:

• Introduces a long-lived defaultSession and refactors many tests to reuse it instead of creating per-test sessions.
• Adds session/settings helpers (GetDefaultSessionSettings(...), OpenSessionManager(), CloseTestSession()) and extends process-output helpers with optional timeouts.
• Initializes several WSLA message struct fields to {} in lxinitshared.h to avoid uninitialized data.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 8 comments.

File	Description
test/windows/WSLATests.cpp	Reworks test setup and many test cases to reuse a default session; adds helper utilities and timeout support.
src/shared/inc/lxinitshared.h	Adds default member initialization for various WSLA message fields.

Comments suppressed due to low confidence (1)

test/windows/WSLATests.cpp:137

• OpenSessionManager() was introduced, but CreateSession() still duplicates the same CoCreateInstance + COM impersonation setup. Consider using OpenSessionManager() inside CreateSession() to keep session-manager initialization consistent and reduce duplicated logic.

    wil::com_ptr<IWSLASession> CreateSession(const WSLA_SESSION_SETTINGS& sessionSettings, WSLASessionFlags Flags = WSLASessionFlagsNone)
    {
        wil::com_ptr<IWSLASessionManager> sessionManager;
        VERIFY_SUCCEEDED(CoCreateInstance(__uuidof(WSLASessionManager), nullptr, CLSCTX_LOCAL_SERVER, IID_PPV_ARGS(&sessionManager)));
        wsl::windows::common::security::ConfigureForCOMImpersonation(sessionManager.get());

[OneBlue]

This was causing all VM's to try to use the same IP address. We should refactor this in the long run, but for now fixed by making sure that configs aren't shared accross sessions

[benhillis]

Since this creates a new line, should this be called ResetTestSession?