Improve caret test by skipping inserter (#32832)

Press Enter after adding intial caption will add a new paragraph,
allowing skipping the insertBlock() with the same functionality.

Local tests runs show saving ~5 seconds on normal test run and
>10 seconds when using THROTTLE_CPU=4 SLOW_NETWORK=true

packages/e2e-tests/specs/editor/blocks/image.test.js

@@ -115,7 +115,7 @@ describe( 'Image', () => {
  const fileName = await upload( '.wp-block-image input[type="file"]' );
  await waitForImage( fileName );
  await page.keyboard.type( '1' );
- await insertBlock( 'Paragraph' );
+ await page.keyboard.press( 'Enter' );
  await page.keyboard.press( 'Backspace' );
  await page.keyboard.type( '2' );