test: Fix flaky integration tests asserting membership in capped iterate() (#824)

### Summary

Several `*_collection_iterate` integration tests created a few
resources, called `iterate(limit=10, desc=True)`, and asserted each
just-created ID showed up. `limit` is a *total* cap, not a per-page size
— under the parallel suite, other workers creating the same resource
type could push the fresh items past the 10-newest window before the
assertion ran.

Dropping `limit=10` lets the iterator walk the full collection
(server-side pagination still chunks the requests), so the inclusion
check runs against the full set instead of a racy window.

### Failing CI runs

- request_queue:
https://github.com/apify/apify-client-python/actions/runs/26398397194/job/77704443961
- dataset:
https://github.com/apify/apify-client-python/actions/runs/26398508480/job/77704799161