Hide count on the work item Epics

What does this MR do and why?

The count started showing on work item Epics after !161888 (merged) was merged. The count and icon are incorrect information as per the anticipated UX. Also, it will be part of Hierarchy widget rollups - Count badge + hover (#474913 - closed). So, this MR just hides the count for work item epics

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.

Screenshots or screen recordings

Screenshots are required for UI changes, and strongly recommended for all other merge requests.

	Before	After
Epic
Objective

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 on Epics:

1. Login with any user
2. Go to Group > Epics
3. Open or create an Epic
4. Create a child item or add an existing child item
5. Check the count in the header of the widget. It should not be displayed.

Steps to verify on Issues:

1. Login with any user
2. Go to Project > Issues
3. Open or create an Issue
4. Create a child item or add an existing child item
5. Verify if the form is closed after the item is added to the list
6. Check the count in the header if the widget. It should be displayed.