Summary

We should stop writing to the cupe_private column in the cu_private_event table, so that we can drop the column once these changes are stably deployed

Background

• T384460: CheckUser: [Proposal] Remove support for storing encrypted recipients of EmailUser emails discusses how the RC4 encryption functionality used by the cupe_private column is deprecated and not present on several systems
  • Therefore, on that task, it was decided to remove the functionality and associated cupe_private column
• This task describes removing any code that writes to cupe_private, including the use of deprecated encryption methods

Acceptance criteria

• No code writes to (or reads from) to cupe_private in the cu_private_event table