Added css class to fix line wrap for assignee label in issues

Fixes #64331

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

-= form.label :assignee_id, "Assignee", class: "col-form-label #{has_due_date ? "col-lg-4" : "col-sm-2"}"
+= form.label :assignee_id, "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|

changelogs/unreleased/64331-Assignee-field-in-a-new-issue-has-an-incorrect-line-wrap.yml

+---
+title: Fixed incorrect line wrap for assignee label in issues
+merge_request: 30523
+author: Marc Schwede
+type: fixed