hypervisors.List() is not implementing pagination correctly

Since microversion 2.53, GET /hypervisors/detail on the Nova API is fully paginated (as is already acknowledged in type ListOpts having limit and marker fields), so the current implementation with SinglePageBase is not sufficient anymore. I got bitten by this because our organization's productive regions actually have more than 1000 hypervisors.

[nova] fix pagination of hypervisors.List()