Rename userId in userSetting to `externalUserId`

[stalniy]

Why

We currently have confusing and inconsistent references around userSetting, caused by the presence/usage of userId inside userSetting.

This is already creating production issues and is likely to keep causing bugs and developer confusion.

What

1. Investigate what is affected. If there are other tables that point to userId in userSetting, leave this task and refactor those first
2. Prepare migration to rename userId in userSetting to externalUserId
3. Run this migration during low usage period

[stalniy]

Affected userAddessName table