Add MR Type trend and backlog charts to Product Planning Team Page

Why is this change being made?

One of the objectives of the Next Prioritization working group is to have MR Type hygiene visible on all team pages, with EMs responsible for maintaining hygiene.

This is a minimal change to add the charts to the groupproduct planning team page before possibly abstracting into a partial or helpers.

Review app: https://jh-update-team-page-with-mr-type-charts.about.gitlab-review.app/handbook/engineering/development/dev/plan-product-planning-certify-be/index.html

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
  • Copy/paste the Slack conversation to document it for later, or upload screenshots. Verify that no confidential data is added.
• Assign reviewers for this change to the correct DRI(s)
  • If the DRI for the page/s being updated isn’t immediately clear, then assign it to one of the people listed in the "Maintained by" section in on the page being edited.
  • 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 affect team members, or warrant an announcement in another way, please consider posting an update in #whats-happening-at-gitlab linking to this MR.
  • If this is a change that directly impacts the majority of global team members, it should be a candidate for #company-fyi. Please work with internal communications and check the handbook for examples.

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