Set guest voume driver as default

[kvega005]

Summary of the Pull Request

Set guest volume driver as the default option. Clean up code and update tests to reflect these changes.

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

The changes include adding a "guest" volume driver alongside the existing options, cleaning up the code, and updating the allow list. Tests have been modified to ensure they correctly validate the new default driver.

Validation Steps Performed

Validated the changes by running existing tests, which all passed successfully. Manual testing confirmed that the "guest" driver functions as expected.

[Copilot]

Pull request overview

This PR changes WSLC volume creation semantics so that the guest volume driver becomes the default when --driver is omitted, and updates end-to-end tests and CLI help expectations to match.

Changes:

• Default the service-side volume driver to guest when no driver is specified.
• Update CLI argument description/help text to show guest as the default driver.
• Update WSLC E2E tests to stop passing VHD-specific options by default and to validate guest as the default driver.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
test/windows/wslc/e2e/WSLCE2EVolumeRemoveTests.cpp	Updates volume-create invocations to rely on the new default driver.
test/windows/wslc/e2e/WSLCE2EVolumeListTests.cpp	Updates list tests to create volumes without VHD-specific options.
test/windows/wslc/e2e/WSLCE2EVolumeInspectTests.cpp	Updates inspect assertions to expect guest as the default driver.
test/windows/wslc/e2e/WSLCE2EVolumeCreateTests.cpp	Updates default-driver test and help-text expectation; removes VHD opts from default-path tests.
test/windows/wslc/e2e/WSLCE2EContainerRunTests.cpp	Updates named-volume test setup to create volumes without VHD-specific options.
src/windows/wslcsession/WSLCSession.cpp	Changes the service default driver from vhd to guest when not specified.
src/windows/wslc/arguments/ArgumentDefinitions.h	Updates CLI --driver argument description to show default guest.

[Copilot]

Pull request overview

Copilot reviewed 7 out of 7 changed files in this pull request and generated no new comments.

[Copilot]

Pull request overview

Copilot reviewed 8 out of 8 changed files in this pull request and generated no new comments.

[OneBlue]

LGTM, feel free to merge after resolving conflicts

[Copilot]

Pull request overview

Copilot reviewed 8 out of 8 changed files in this pull request and generated 1 comment.

Comments suppressed due to low confidence (1)

test/windows/wslc/e2e/WSLCE2EVolumeRemoveTests.cpp:69

• This test previously exercised volume remove against volumes created using the vhd flow (via SizeBytes opts). With the default now "guest", it no longer validates that volume remove still correctly deletes vhd-backed volumes (including any vhd-specific cleanup paths). Consider keeping at least one remove scenario that creates a vhd volume explicitly (--driver vhd with required opts) and then removes it.

    WSLC_TEST_METHOD(WSLCE2E_Volume_Remove_Valid)
    {
        auto result = RunWslc(std::format(L"volume create {}", TestVolumeName));
        result.Verify({.Stderr = L"", .ExitCode = 0});

        VerifyVolumeIsListed(TestVolumeName);

        result = RunWslc(std::format(L"volume remove {}", TestVolumeName));
        result.Verify({.Stdout = std::format(L"{}\r\n", TestVolumeName), .Stderr = L"", .ExitCode = 0});