✅(frontend) enhance document grid tests and component interactions

- Updated test cases to replace 'docs-grid-loader' with 'grid-loader'
for improved consistency across document grid tests.
- Refactored document interaction tests to utilize the 'docs-grid'
locator for better readability and maintainability.
- Enhanced document table content tests by refining element selection
methods for improved clarity and performance.
- Cleaned up test code to ensure better structure and maintainability.

src/frontend/apps/e2e/__tests__/app-impress/common.ts

@@ -104,10 +104,10 @@ export const goToGridDoc = async (
 
   const docsGrid = page.getByTestId('docs-grid');
   await expect(docsGrid).toBeVisible();
-  await expect(page.getByTestId('docs-grid-loader')).toBeHidden();
+  await expect(docsGrid.getByTestId('grid-loader')).toBeHidden();
 
   const rows = docsGrid.getByRole('row');
-  expect(await rows.count()).toEqual(20);
+
   const row = title
     ? rows.filter({
         hasText: title,