chore: re-implement stack-too-deep fix

I previously implemented this fix, then reverted it as not needed.
Now upon merging with m2-mainnet, `registerOperatorWithChurn` has an additional input.
This is reintroducing the same stack-too-deep error
so I am reintroducing the same fix (one less local var)

src/RegistryCoordinator.sol

@@ -252,16 +252,16 @@ contract RegistryCoordinator is
         });
 
         for (uint256 i = 0; i < quorumNumbers.length; i++) {
-            uint8 quorumNumber = uint8(quorumNumbers[i]);
-            OperatorSetParam memory operatorSetParams = _quorumParams[quorumNumber];
+            // reference: uint8 quorumNumber = uint8(quorumNumbers[i]);
+            OperatorSetParam memory operatorSetParams = _quorumParams[uint8(quorumNumbers[i])];
 
             /**
              * If the new operator count for any quorum exceeds the maximum, validate
              * that churn can be performed, then deregister the specified operator
              */
             if (results.numOperatorsPerQuorum[i] > operatorSetParams.maxOperatorCount) {
                 _validateChurn({
-                    quorumNumber: quorumNumber,
+                    quorumNumber: uint8(quorumNumbers[i]),
                     totalQuorumStake: results.totalStakes[i],
                     newOperator: msg.sender,
                     newOperatorStake: results.operatorStakes[i],