When the multi-cluster version of the cluster list requests data (either subscription for global or clusters for regionalized) it sets a page size of 1000.  

When testing the cluster list, this limit of 1000 causes poor performance from some API requests. 

Through trial and error (see the comments in OCMUI-1632) a size of 500 was recommended.

The purpose of this task is to set the request size to 500.

Because this feature is behind a feature flag and will be tested as part of OCMUI-1632 - this specific task does not require QE testing.