Add some tests to demonstrate an estimate of the nominator limit (#2724)

* Add some tests to demonstrate an estimate of the nominator limit

* Update runtime/kusama/src/lib.rs

* Update runtime/polkadot/src/lib.rs

Co-authored-by: Shawn Tabrizi <shawntabrizi@gmail.com>

* Fix build

* remove max

Co-authored-by: Shawn Tabrizi <shawntabrizi@gmail.com>