Remove redundant "Successfully signed out" notification

[Copilot]

This PR removes the redundant "Successfully signed out" notification that appears when users sign out from an account in VS Code.

Problem

When users sign out from an account, VS Code shows a toast notification saying "Successfully signed out." However, this notification is redundant because:

• The Account view already provides visual feedback through UI changes (badges, sign-in prompts)
• Users can see their signed-out status in the Account view immediately
• The notification adds unnecessary noise to the user experience

Solution

Removed the single line of code that triggers the notification in the MainThreadAuthenticationProvider.removeSession() method:

// Before
async removeSession(sessionId: string): Promise<void> {
    await this._proxy.$removeSession(this.id, sessionId);
    this.notificationService.info(nls.localize('signedOut', "Successfully signed out."));
}

// After  
async removeSession(sessionId: string): Promise<void> {
    await this._proxy.$removeSession(this.id, sessionId);
}

Impact

• Users will no longer see the redundant toast notification when signing out
• The Account view continues to provide all necessary visual feedback about authentication status
• Core authentication functionality remains unchanged
• No breaking changes to the authentication API

Fixes #233400.

Warning

Firewall rules blocked me from connecting to one or more addresses

I tried to connect to the following addresses, but was blocked by firewall rules:

• electronjs.org
  • Triggering command: node-gyp (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to my firewall allow list

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[TylerLeonhardt]

Fix this error:

[tsec-compile-check ] src/vs/workbench/api/browser/mainThreadAuthentication.ts(56,20): error TS6138: Property 'notificationService' is declared but its value is never read.

[Copilot]

Fix this error:

[tsec-compile-check ] src/vs/workbench/api/browser/mainThreadAuthentication.ts(56,20): error TS6138: Property 'notificationService' is declared but its value is never read.

Fixed in commit e6564c9. Removed the unused notificationService parameter from the MainThreadAuthenticationProvider constructor and updated the instantiation accordingly.