title: gitlab not expanding variable used in parallel/matrix
body: <p>I am trying to pass the variable to parallel/matrix and do not see that getting expanded and the job failing. This is being set in the job from the environment variable. I am trying to echo the variable in script and see it shows the right value, but does not get substituted in parallel/matrix. Am I missing anything?</p>
  <pre><code>.common_deploy:
    script:
      - |
        echo &quot;showing the regions from environment&quot;
        echo $qa_regions
        echo &quot;showing the regions from job variable&quot;
        echo $REGIONS
    parallel:
      matrix:
        - REGION: &quot;${REGIONS}&quot;
        
  DeployToQA:
    variables:
      ENVIRONMENT: qa
      REGIONS: $qa_regions
    extends:
      - .common_deploy
    stage: deploy
    rules:
      - if: '$CI_PIPELINE_SOURCE == &quot;push&quot; &amp;&amp; $CI_COMMIT_BRANCH == &quot;master&quot;'
        allow_failure: true
  </code></pre>
  <p>Here the variable <code>$qa_regions</code> has the value of &quot;us-west-2,us-east-1&quot;, I was expecting to see the 2 jobs for those regions , but i am seeing the job as <code>DeployToQA: [${REGIONS}]</code></p>