Add logic to avoid running PHPUNIT if the project has no phpunit tests
>>> [!note] Migrated issue
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Reported by: [jonathan1055](https://www.drupal.org/user/92645)
Related to !139
>>>
<h3 id="summary-problem-motivation">Problem/Motivation</h3>
<p>From <span class="drupalorg-gitlab-issue-link project-issue-status-info project-issue-status-7"><a href="https://www.drupal.org/project/gitlab_templates/issues/3397270" title="Status: Closed (fixed)">#3397270: Nightwatch testing against all opted in versions</a></span></p>
<blockquote><p>[the phpunit failure] is only happening because the phpunit job is assumed to always run unless one explicitly opts out by setting SKIP_PHPUNIT='1'. Arguably we should have similar <code>exists</code> logic for PHPUnit, then projects like Decoupled Pages or CKEditor 5 Paste Filter, which have only Nightwatch, would no longer have to set SKIP_PHPUNIT.
</p></blockquote>
<p>In addition to the normal opt-in and skip- rules, Nightwatch tests include</p>
<pre> - exists:<br> - tests/src/Nightwatch/**/*.js<br> - modules/*/tests/src/Nightwatch/**/*.js<br> when: on_success</pre><h3 id="summary-proposed-resolution">Proposed resolution</h3>
<p>Add similar <code>exists</code> checks in phpunit, to only attempt to run if the project actually has phpunit tests.</p>
<h3 id="summary-remaining-tasks">Remaining tasks</h3>
issue