Hide merged date sort option for open/closed MRs page

What does this MR do and why?

When listing open and closed MRs, sorting by merged date does not make sense since they are not merged.

This hides the option and reverts back to default sorting on those pages when user preferences have a sorting preference set to merged date.

How to set up and validate locally

1. View a list of MRs for a certain project.
2. View the Open/Closed tabs and see that Merged date sorting option is no longer present.

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 #383606 (closed)