V2Wizard: Change search parameter from qcow to qcow2

`target=qcow2` is in better alignment with the UI than `target=qcow`

src/test/Components/CreateImageWizardV2/steps/ImageOutput/TargetEnvironment.test.tsx

@@ -338,7 +338,7 @@ describe('set target using query parameter', () => {
   });
 
   test('guest-installer (query parameter provided)', async () => {
-    await render({ target: 'qcow' });
+    await render({ target: 'qcow2' });
     await clickToReview();
     const targetExpandable = await screen.findByRole('button', {
       name: /Target environments/,