[Dashboard] Update embed mode tests (#179171)

Part of #176882

## Summary

Due to a chrome update in the CI environment, screenshot tests started
failing and were skipped - this PR updates the embed mode baseline
screenshots so that the failing tests can be unskipped.

### Checklist

- [x] [Unit or functional
tests](https://www.elastic.co/guide/en/kibana/master/development-tests.html)
were updated or added to match the most common scenarios


### For maintainers

- [ ] This was checked for breaking API changes and was [labeled
appropriately](https://www.elastic.co/guide/en/kibana/master/contributing.html#kibana-release-notes-process)

test/functional/apps/dashboard/group5/embed_mode.ts

@@ -24,8 +24,7 @@ export default function ({
   const screenshot = getService('screenshots');
   const log = getService('log');
 
-  // Failing: See https://github.com/elastic/kibana/issues/176882
-  describe.skip('embed mode', () => {
+  describe('embed mode', () => {
     /*
      * Note: The baseline images used in all of the screenshot tests in this test suite were taken directly from the CI environment
      * in order to overcome a known issue with the pixel density of fonts being significantly different when running locally versus