Test chunk validator rewards for stateless validation

[tayfunelmas]

Task is to make sure validator rewards are working as intended in mocknet.

Relevant PR: https://github.com/near/nearcore/pull/11121/files

[tayfunelmas]

RE rewards calculation: the problem with reward calculation not working is due to inflation rate set to 0 in genesis for mocknet. similar to the protocol_reward_rate problem, that the code is picking it from genesis config instead of hard-coded value or 1/20 (mainnet uses hard-coded but mocknet using genesis because protocol version starts from the genesis version):

nearcore/chain/epoch-manager/src/reward_calculator.rs

Line 56 in f7617f0

if use_hardcoded_value { Rational32::new_raw(1, 20) } else { self.max_inflation_rate };