Add database-chosen to the structured log

What does this MR do?

SidekiqServerMiddleware will set job[database_chosen] based on the option if we have decided to hit the primary database, replica, or we will retry the job because the database replica is not caught up.

It would be useful to have this value in the sidekiq structured log as well.

Screenshots (strongly suggested)

Does this MR meet the acceptance criteria?

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