ToolbarClaroOverridesTest fails intermittently

Problem/Motivation

See https://git.drupalcode.org/project/drupal/-/jobs/94869

PHPUnit Test failed to complete; Error: PHPUnit 9.6.8 by Sebastian Bergmann
    and contributors.
    
    Testing Drupal\Tests\system\Functional\Theme\ToolbarClaroOverridesTest
    F                                                                   1 / 1
    (100%)
    
    Time: 00:08.330, Memory: 4.00 MB
    
    There was 1 failure:
    
    1)
    Drupal\Tests\system\Functional\Theme\ToolbarClaroOverridesTest::testClaroAssets
    Failed asserting that false is true.
    
    /builds/project/drupal/vendor/phpunit/phpunit/src/Framework/Constraint/Constraint.php:122
    /builds/project/drupal/vendor/phpunit/phpunit/src/Framework/Constraint/Constraint.php:55
    /builds/project/drupal/core/modules/system/tests/src/Functional/Theme/ToolbarClaroOverridesTest.php:141
    /builds/project/drupal/vendor/phpunit/phpunit/src/Framework/TestResult.php:728
    
    FAILURES!
    Tests: 1, Assertions: 36, Failures: 1.
    
    HTML output was generated
    http://localhost/subdirectory/sites/simpletest/browser_output/Drupal_Tests_system_Functional_Theme_ToolbarClaroOverridesTest-1-15023582.html
    http://localhost/subdirectory/sites/simpletest/browser_output/Drupal_Tests_system_Functional_Theme_ToolbarClaroOverridesTest-2-15023582.html
    http://localhost/subdirectory/sites/simpletest/browser_output/Drupal_Tests_system_Functional_Theme_ToolbarClaroOverridesTest-3-15023582.html
    http://localhost/subdirectory/sites/simpletest/browser_output/Drupal_Tests_system_Functional_Theme_ToolbarClaroOverridesTest-4-15023582.html
    http://localhost/subdirectory/sites/simpletest/browser_output/Drupal_Tests_system_Functional_Theme_ToolbarClaroOverridesTest-5-15023582.html

Steps to reproduce

Proposed resolution

Remaining tasks

User interface changes

API changes

Data model changes

Release notes snippet