Import missing EE counterpart of work_item_metadata_widgets

What does this MR do and why?

Import missing EE counterpart of work_item_metadata_widgets in linked items fragment

MR acceptance checklist

Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

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Before	After

How to set up and validate locally

Prerequisites:

1. Enable the OKRs feature as mentioned in the OKRs docs (e.g. ::Feature.enabled?(:okrs_mvc, Project.find(<PROJECT_ID>)) and the namespace must have Ultimate plan).
2. Enable Epic work items
   1. Feature.enable(:work_item_epics_rollout)
   2. Feature.enable(:work_item_epics)

Steps to verify:

1. Login with any user
2. Go to Group > Epics
3. Open or create an Epic
4. Add a linked item with few scoped labels
5. Check of the scoped labels are properly rendered

app/assets/javascripts/work_items/graphql/add_linked_items.mutation.graphql

 #import "./work_item.fragment.graphql"
-#import "./work_item_metadata_widgets.fragment.graphql"
-#import "./work_item_metadata_widgets_extras.fragment.graphql"
 #import "./work_item_linked_items.fragment.graphql"
 
 mutation addLinkedItems($input: WorkItemAddLinkedItemsInput!) {