Machine listing pagination displays incorrect total number of pages

### Description
Machine listing pagination displays incorrect total number of pages.

Machine list pagination is calculating the total number of pages from count and page_size. This does not take into account collapsed groups and may result in an incorrect number of total pages being displayed.

MAAS UI should use instead the total_pages property returned by the API machine.list.

### Steps to reproduce:
- Go to machine listing on a MAAS with multiple machines
- If needed, you can set the page size manually to a low value in developer tools console by typing `localStorage.setItem("machineListPageSize", "1")` and refreshing the page
- collapse a group of machines and take note of the total number of pages
- expand a group of machines

#### Expected:
the total number of machines should update

#### Actual:
the total number of machines does not update and is incorrect