GET /users to operate in paginated mode only

[apederson94]

From https://smartsheet.slack.com/archives/C04LCSNP3FX/p1719915705398569

We are changing this API to operate in paginated mode only, maxed at 2k, specifically:
The includeAll parameter (if true, includes all results) will be removed from the API contract. We will continue to support it by returning results with page=1 and pageSize=2000 to minimize impacts on established customers' automations. However, for our internal service teams, please do not use this parameter and instead, paginate your requests.
The pageSize parameter will have a maximum allowed value of 2000. If a pageSize greater than 2000 is provided, a 400 Bad Request status code with error code 1229 will be returned.