Add alert dismiss to all Aztec UI tests

[guarani]

A follow-up to #16118 to make all Aztec UI tests dismiss the "classic editor deprecation" alert. Otherwise tests will fail if testBasicPostPublish is not run before the other tests. (Although this doesn't happen at the moment since Xcode runs tests in alphabetical order, it might happen if tests are renamed/removed/etc.)

To test:

1. (Optional) On a clean simulator (without WordPress installed), checkout this branch and run only the testTextPostPublish test, ensure it passes
2. Run optional UI tests (on any device) and make sure they pass (I've done this below)
3. Check The Run UI Tests job and make sure tests passed on the first run

PR submission checklist:

• I have considered adding unit tests where possible.
• I have considered adding accessibility improvements for my changes.
• I have considered if this change warrants user-facing release notes and have added them to RELEASE-NOTES.txt if necessary.

[peril-wordpress-mobile]

You can trigger an installable build for these changes by visiting CircleCI here.

[peril-wordpress-mobile]

You can trigger optional UI/connected tests for these changes by visiting CircleCI here.

[guarani]

Hey @jkmassel, sorry for another PR review. This is fixes an oversight in the previous PR you reviewed for me.

[guarani]

I checked all the test steps above, so it might not be necessary to test this locally yourself.

[jkmassel]

Tested it locally because I didn't see your comment before I did 😅