Perf tests: make pages test compatible with base branch (#63204)

Co-authored-by: ellatrix <[email protected]>
Co-authored-by: youknowriad <[email protected]>

test/performance/specs/site-editor.spec.js

@@ -416,14 +416,22 @@ test.describe( 'Site Editor Performance', () => {
  } )
  );
 
+ await admin.visitSiteEditor();
+ await page.getByRole( 'button', { name: 'Pages' } ).click();
+
+ // Check if we're dealing with the old URL structure.
+ const path = new URL( page.url() ).searchParams.get( 'path' );
+
  const samples = 10;
  for ( let i = 1; i <= samples; i++ ) {
  // Start from the trash view, then navigate to all pages, so we
  // test item loading rather than site editor load as a whole.
  // For some reason `visiSiteEditor` does not work with these
  // parameters.
  await admin.visitAdminPage(
- 'site-editor.php?postType=page&layout=table&activeView=trash'
+ path
+ ? 'site-editor.php?path=%2Fpage&layout=table&activeView=trash'
+ : 'site-editor.php?postType=page&layout=table&activeView=trash'
  );
 
  const startTime = performance.now();