Change team pillar from "brand research" to "brand tracking"

Why is this change being made?

To more accurately describe what our team is focused on in this fiscal year, we're renaming the pillar "brand research" to "brand tracking" in all instances. This MR updates the Brand Strategy team page to be sure we're accurately reflecting our team's work.

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
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  • 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.

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