Referrers "View more" is sometimes hidden

### Impacted plugin

None / Other

### Quick summary

Stats on Jetpack app

When some of the referrers are marked as a spam, they're not returned from the API. However, the endpoint still counts them in the limit and this causes the "View more" item to be incorrectly invisible. This needs to be fixed on the API.

### Steps to reproduce

1. Mark your referrers between position 1 and 6 as spam
2. Go to Stats/Referrers block
3. Notice that the referrers you marked as a spam are invisible
4. Notice that there are no referrers replacing them and the "View more" item is not visible

### A clear and concise description of what you expected to happen.

When referrers are marked as spam, they shouldn't be counted in the limit.
Then 'View more' could function properly

### What actually happened

the endpoint still counts them in the limit and this causes the "View more" item to be incorrectly invisible. This needs to be fixed on the API.

### Impact

Some (< 50%)

### Available workarounds?

No and the platform is unusable

### Platform (Simple and/or Atomic)

_No response_

### Logs or notes

_No response_

Start by locating the API endpoint used by the Stats/Referrers block in Jetpack and trace how spam referrers are filtered and counted. Reproduce the case where positions 1–6 are marked as spam, then verify that excluded referrers no longer consume the limit and that the “View more” item appears when additional results exist.

Written by the indexing model from the issue text.