Service Desk SEG: Add email obfuscation feature to current focus

Why is this change being made?

The work in Obfuscate issue email participants based on mem... (gitlab-org/gitlab!108901 - merged) will ship in 15.9 and we should add that to the current focus, because it contributes to the success of Service Desk as a category.

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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