When re-authenticating user should not be asked to delete their account.

Currently, when users attempt to re-authenticate their GitLab account in the VS Code extension using the GitLab: Authenticate command, they encounter an unnecessary friction point. The extension prompts them to manually delete their existing account credentials before they can proceed with re-authentication.

Current Behavior

1. User executes GitLab: Authenticate command
2. Extension detects an existing authenticated session
3. User is presented with a prompt/message requiring them to delete the current account first
4. User must manually remove the existing account
5. Only then can they proceed with the authentication process

Expected Behavior

The re-authentication flow should be seamless:

1. User executes GitLab: Authenticate command
2. Extension automatically handles the existing session (either by replacing it or prompting for confirmation to replace)
3. User proceeds directly to the authentication flow without manual deletion steps