ImageTest::testWidth() has wrong selector, but no assertion: increases DrupalCI by 20 seconds

Problem/Motivation

Discovered while working on #3224652: [drupalImage] Add ckeditor5-image's imageresize plugin to allow image resizing.

$assert_session->waitForElementVisible('css', '.figure.image')

is wrong, it should be figure.image.

Steps to reproduce

N/A

Proposed resolution

1. Assert the result: guarantees the selector works; should fail tests
2. Fix selector; should make tests pass again

Remaining tasks

Review

User interface changes

N/A

API changes

N/A

Data model changes

N/A

Release notes snippet

N/A