Update "Export Issues CSV file" tier

Why is this change being made?

As per gitlab-org/gitlab#212330 (closed) and gitlab-org/gitlab!28703 (merged), that move seems to have been completed, but not yet advertised everywhere.

Thanks to @mhuseinbasic for highlighting this in a Zendesk ticket!

Author Checklist

• Provided a concise title for the MR
• Added a description to this MR explaining the reasons for the proposed change, per say-why-not-just-what
• Assign this change to the correct DRI
  • If the DRI for the page/s being updated isn’t immediately clear, then assign it to your manager.
  • If your manager does not have merge rights, please ask someone to merge it AFTER it has been approved by your manager in #mr-buddies.
  • If the changes relate to any part of the project other than updates to content and/or data files please make sure to ping @gl-static-site-editor in a comment for a review and merge. For example changes to .gitlab-ci.yml, JavaScript/CSS/Ruby code or the layout files.

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