Address differences between Legacy Epics and Work Items Child items widget

Problem

There are few differences between Legacy Epic's and Work Item's Child items widget if we compare both the widgets side by side.

• In legacy view, when an epic is added, the list becomes disable until the API response is returned. Disable the list for work item's Child items widget also. - !161574 (merged)

  

• Currently, when an item is removed from the work items Child item widget, the loader is shown on the collapse button in the left. No loader is needed as per the discussion. - !161906 (merged)

  

• The form closes when an epic is created or added in the legacy view Child items. This does not happen on the work items. - !161753 (merged)

• Move the show labels under the kebab menu to have proper mobile view. This is tracked via #463654 (closed). Other references - #443830 (closed).