Use the term `CFP` consistently in the handbook

Why is this change being made?

Follow-up from !106770 (merged) to consistently use CFP in the handbook.

A global find/sed command helped, there is one location in the handbook that embeds an SVG though and needed a revert.

find sites/handbook/source/handbook -type f -name '*md*' -exec sh -c 'sed -i "s,CfP,CFP,g" "{}"' \;

git checkout sites/handbook/source/handbook/customer-success/demo-systems/tutorials/integrations/create-jenkins-pipeline/index.html.md

We do not use markdownlint like in the GitLab docs yet, to ban words in CI/CD pipeline runs.

Author Checklist

• Provided a concise title for this Merge Request (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 MR to the correct Directly Responsible Individual/s (DRI)
  • 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 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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