After this change, for SERVER-89650 index_stats.js began failing under some suites e.g., unsplittable_collections_created_on_any_shard_jscore_passthrough.yml as a retry after a failure due to a StaleConfig led to stats being incremented again.

While it's reasonable that index_stats.js should expect exact stat values to verify correct behaviour, in the presence of retries a strict == 1 on index use count may fail without indicating any real issue.

As it can still verify that the expected index is used while in suites which may require retries, relax this check to >= 1.