[Whitelisted Caller] Increase validator set size to 500

Whitelisted by: https://collectives.subsquare.io/fellowship/referenda/220?tab=call

This call increases the current validator set size from 400 to 500, this a followup of https://polkadot.subsquare.io/referenda/1129, that increased the validator set size from 297 to 400.

Following this change the maximum number of usable cores supported by polkadot will increase from 80(400 / 5) to 100 (500 / 5) where 5 is the dimension of a parachain backing group.

Additionally, this reverts back the maximum number of validator candidates to 2000, that was modified in https://polkadot.subsquare.io/referenda/1129, because it is not needed until we decide to increase the validator set size to 1000.

Testing

Kusama has been running with 500 parachain consensus validators for 3 months since this referenda passed: https://kusama.subsquare.io/referenda/416

Edited

Summary of Validator Set Size Increase

Current Change: Increase validator set size from 400 to 500.
Previous Change: Increased from 297 to 400 (Referendum 1129).
Impact: Increases usable cores from 80 to 100 (500 / 5).
Parachain Backing Group: Dimension remains 5.
Validator Candidates: Reverts max candidates to 2000 (not needed until set size reaches 1000).
Testing on Kusama: 500 validators have been running for 3 months (Referendum 416).

Source

Whitelisted by: https://collectives.subsquare.io/fellowship/referenda/220?tab=call

This call increases the current validator set size from 400 to 500, this a followup of https://polkadot.subsquare.io/referenda/1129, that increased the validator set size from 297 to 400.

Following this change the maximum number of usable cores supported by polkadot will increase from 80(400 / 5) to 100 (500 / 5) where 5 is the dimension of a parachain backing group.

Testing

Kusama has been running with 500 parachain consensus validators for 3 months since this referenda passed: https://kusama.subsquare.io/referenda/416

Edited