20496 make max_page_size upper bound

[arthanson]

Fixes: #20496

Refactors and fixes REST paginator checking for MAX_PAGE_SIZE, making it the upper bound.

if MAX_PAGE_SIZE is set:

• if no limit is set return min(MAX_PAGE_SIZE, PAGINATE_COUNT)
• if limit set return min(limit, MAX_PAGE_SIZE)
• if limit = 0 or None return MAX_PAGE_SIZE

if MAX_PAGE_SIZE is not set:

• if no limit is set return PAGINATE_COUNT
• if limit is set return limit
• if limit = 0 return all data

Note: The UI view overrides this if you set the pagination limit dropdown - i.e. if you select in the UI 1000 items and MAX_PAGE_SIZE=100, then 1000 items will still be returned in the view, which I think is correct.