NR Log browser - 'load earlier' not behaving

### Current Behavior

With the new ability to browse to earlier logs but timestamp, the 'load earlier' link doesn't behaviour.

It appears to load the earlier logs from the time that was originally shown, and not earlier relative to the time that was browsed to.

My guess in the pagination key isn't being updated when browsing by time.

### Expected Behavior

Clicking 'load earlier' should load earlier relative to what I can see

### Steps To Reproduce

_No response_

### Environment

- FlowFuse version:
- Node.js version:
- npm version:
- Platform/OS:
- Browser:

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

I have provided an initial effort estimate