Update community-relations sources in redirects.yml

Why is this change being made?

The redirects configuration for the renaming from community relations to developer-relations handbook in !124139 (merged) was causing 404s, which included duplicated slashes in the URL string.

Examples:

https://about.gitlab.com/handbook/marketing/community-relations/ => 
https://about.gitlab.com/handbook/marketing/developer-relations//

https://about.gitlab.com/handbook/marketing/community-relations/developer-evangelism/workflow/ => 
https://about.gitlab.com/handbook/marketing/developer-relations//developer-evangelism/workflow/

The regex comparison operator behaves differently to the exact match operator - the first sources string that matches, will be analyzed and replaced in the string. If the trailing slash is not included the sources entry, it won't get removed by the replacement that already contains a trailing slash.

The fix is provide the exact same pattern in sources and targets, following the same trailing slashes string pattern, when using the regex comp_op.

The detailed analysis and solution is in !125279 (comment 1418319598)

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, and the content is SAFE
• 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
  • The when to get approval handbook section explains the workflow in more detail
• 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.

---