Fix E2E tests in WordPress 5.8

[spacedmonkey]

Feature Description

The following E2E tests are failing in WordPress 5.8.

● Web Stories Block › should insert a new web stories block

    TimeoutError: waiting for function failed: timeout 3000ms exceeded

      28 |  */
      29 | async function waitForInserterCloseAndContentFocus() {
    > 30 |   await page.waitForFunction(() =>
         |              ^
      31 |     document.body
      32 |       .querySelector('.block-editor-block-list__layout')
      33 |       ?.contains(document.activeElement)

      at new WaitTask (../../../node_modules/puppeteer/src/common/DOMWorld.ts:777:28)
      at DOMWorld.waitForFunction (../../../node_modules/puppeteer/src/common/DOMWorld.ts:699:22)
      at Frame.waitForFunction (../../../node_modules/puppeteer/src/common/FrameManager.ts:1241:28)
      at Page.waitForFunction (../../../node_modules/puppeteer/src/common/Page.ts:3152:29)
      at waitForInserterCloseAndContentFocus (../../e2e-test-utils/src/insertBlock.js:30:14)
      at insertBlock (../../e2e-test-utils/src/insertBlock.js:50:9)
      at Object.<anonymous> (specs/wordpress/webStoriesBlock.js:90:5)

  ● Web Stories Block › should insert a new web stories block and select story

    TimeoutError: waiting for function failed: timeout 3000ms exceeded

      28 |  */
      29 | async function waitForInserterCloseAndContentFocus() {
    > 30 |   await page.waitForFunction(() =>
         |              ^
      31 |     document.body
      32 |       .querySelector('.block-editor-block-list__layout')
      33 |       ?.contains(document.activeElement)

This is because the block insert has changed and inserter doesn't close as it once did. We will need to write some conditional logic here to get the insertBlock util to work in multiple versions of WP.

Alternatives Considered

Additional Context

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Acceptance Criteria

Implementation Brief