Adapt results count displayed in nuxeo-results when total count is unknown

Following the fix done for NXP-30633, the total count (aka results count in paginated lists returned by the rest API) cannot be computed within the MongoDB socket timeout because there are too many results.

When this occurs, we will return a total count of -2 meaning it is unknown.

We should adapt the results count displayed in nuxeo-results element.

Attached screenshot (before.png) shows how the Web UI will display the result counts when MongoDB times out. We must improve to a generic label like "Many results"