Replace fragmented page loading state management

### Description

All instances of custom loading state management should be replaced with the new page loader.

A quick search for `loading: false` within the `frontend/src/pages` directory will identify these independent implementations. To ensure a smooth transition, these updates should be grouped into digestible chunks (e.g., by feature or route) as the logic is migrated to the new loader.

Sub tasks should be appended to this issue.

### Epic/Story

_No response_

### Have you provided an initial effort estimate for this issue?

I have provided an initial effort estimate