Remove deprecation for state in MR webhook payload

What does this MR do and why?

As discussed in #367262 (closed) (comment 1222868640), it is still convenient to have state in the MR webhook payload.

This removes the deprecation for the state field.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #367262 (closed)