Pluralize Assignee & Reviewers in MR Form

Issue: https://gitlab.com/gitlab-org/gitlab/-/issues/244835

app/views/shared/issuable/form/_metadata_issuable_assignee.html.haml

-= form.label :assignee_id, "Assignee", class: "col-form-label #{has_due_date ? "col-md-2 col-lg-4" : "col-sm-2"}"
+= form.label :assignee_id, issuable.assignees.size > 1 ? _('Assignee').pluralize : _('Assignee'), class: "col-form-label #{has_due_date ? "col-md-2 col-lg-4" : "col-sm-2"}"
 .col-sm-10{ class: ("col-md-8" if has_due_date) }
   .issuable-form-select-holder.selectbox
     - issuable.assignees.each do |assignee|

app/views/shared/issuable/form/_metadata_issuable_reviewer.html.haml

-= form.label :reviewer_id, "Reviewer", class: "col-form-label #{has_due_date ? "col-md-2 col-lg-4" : "col-sm-2"}"
+= form.label :reviewer_id, issuable.reviewers.size > 1 ? _('Reviewer').pluralize : _('Reviewer'), class: "col-form-label #{has_due_date ? "col-md-2 col-lg-4" : "col-sm-2"}"
 .col-sm-10{ class: ("col-md-8" if has_due_date) }
   .issuable-form-select-holder.selectbox
     - issuable.reviewers.each do |reviewer|

ee/changelogs/unreleased/244835-update-mr-form-to-use-plural-field-names.yml

+---
+title: Resolve Update MR form to use plural field names
+merge_request: 41402
+author:
+type: changed