Remove wsl.conf modification during installation for new WSL architecture

[Copilot]

New WSL architecture automatically handles default user configuration during installation, making the manual /etc/wsl.conf modification unnecessary. However, explicit user changes via config --default-user should still update configuration files, now including /etc/wsl-distribution.conf.

Changes

Installation flow

• Added SetDefaultUserDuringInstall() that only calls WslConfigureDistribution() without modifying wsl.conf
• Modified InstallDistribution() to use new function instead of SetDefaultUser()

Explicit user change flow

• Enhanced SetDefaultUser() to also update /etc/wsl-distribution.conf via new ChangeDefaultUserInWslDistributionConf()
• Maintains existing wsl.conf modification behavior

Implementation

// New function for installation - no wsl.conf modification
HRESULT SetDefaultUserDuringInstall(std::wstring_view userName)
{
    const ULONG uid = DistributionInfo::QueryUid(userName);
    return g_wslApi.WslConfigureDistribution(uid, WSL_DISTRIBUTION_FLAGS_DEFAULT);
}

// Enhanced SetDefaultUser now updates wsl-distribution.conf
HRESULT DistributionInfo::ChangeDefaultUserInWslDistributionConf(const ULONG uid)
{
    // Creates or updates /etc/wsl-distribution.conf with DEFAULT_UID=<uid>
}

Impact

Scenario	Before	After
Installation	wsl.conf + UID	UID only
Config command	wsl.conf + UID	wsl.conf + wsl-distribution.conf + UID

Original prompt

for the new wsl architecture is not needed anymore to add an entry in wsl.conf with the username when pengwin is installed, leave it when the default user is changed and also add the modification of /etc/wsl-distribution.conf to reflect the change of the user id

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