Prevent composer (next major) dependency conflicts in CI
>>> [!note] Migrated issue
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Reported by: [balintbrews](https://www.drupal.org/user/613760)
Related to !184
>>>
<p>After the <span class="drupalorg-gitlab-issue-link drupalorg-gitlab-link-wrapper"><a href="https://git.drupalcode.org/project/gitlab_templates/-/issues/3567692" class="drupalorg-gitlab-link">https://git.drupalcode.org/project/gitlab_templates/-/issues/3567692</a></span> landed in GitLab Templates, which sets <code>CORE_MAJOR_DEVELOPMENT: 'main-dev'</code>, the <code>composer (next major)</code> job started failing with dependency resolution errors. </p>
<p>Let's remove <code>OPT_IN_TEST_NEXT_MAJOR: "1"</code>, so we don't start testing on D12 yet. This aligns with Canvas’s CI configuration.</p>
issue