Fix failing tests

Problem/Motivation

The following tests are failing on the release branch:

• FunctionalJavascript\EntityEmbedTest
• FunctionalJavascript\CardinalityTest
• entity_browser_example\FunctionalJavascript\EntityBrowserExampleTest
• Kernel\Plugin\FieldWidgetDisplayTest
• FunctionalJavascript\InlineEntityFormTest

Steps to reproduce

see https://git.drupalcode.org/project/entity_browser/-/jobs/9267875

Proposed resolution

1. CardinalityTest — Fixable: method casing bug

Six calls use assertCheckBoxExistsByValue / assertCheckBoxNotExistsByValue (capital B) but the base class defines assertCheckboxExistsByValue / assertCheckboxNotExistsByValue (lowercase b). PHP method calls are case-insensitive on most setups, but PHPUnit's __call magic method dispatching can be case-sensitive. This is the likely cause.

2. EntityBrowserExampleTest — Fixable: core: 8.x in view configs

Both example view configs have core: 8.x which is invalid for Drupal 10+. Config validation during module install would fail, causing the testExampleInstall() test to crash at setUp.

3. FieldWidgetDisplayTest — Harder to diagnose remotely

The kernel test creates comment entities. Possible issues include missing schema install (comment.schema.yml), or changes to comment_type entity validation in newer Drupal.

4. EntityEmbedTest — Likely environmental

The CKEditor 5 config looks correct. This may fail due to embed/entity_embed module version incompatibility, or WebDriver timing issues with the CKEditor 5 widget. Hard to diagnose without the actual error output.

5. InlineEntityFormTest — Likely timing/AJAX issues

Uses conditional coreVersion() checks for AJAX waits. Probably flaky due to Drupal 10.2+ AJAX behavior changes.

Remaining tasks

Make a MR.