Hide project name in project activities

## What does this MR do?

- hide namespace and project name on project activity page

## Are there points in the code the reviewer needs to double check?

- did `.event_label` have any meaning?

## Why was this MR needed?

- all events on project activity page are from the same project, so the information was redundant

## What are the relevant issue numbers?

closes #18963

## Screenshots

### Before

![events-before](/uploads/76336e3f5cb08d4ef984df73c89aa90f/events-before.png)

### After

![events-after](/uploads/4a10718ed32960efc115d7854e5cad68/events-after.png)

![after-john-activity](/uploads/d9d151a829d8d32136525e8eb7ea04ad/after-john-activity.png)


See merge request !5068