chore: add event to dsf reset on full withdrawal (#1270)

**Motivation:**

DSF reset isn't emitting event on a full withdrawal.

**Modifications:**

Added event and shadowed declaration to resolve stack too deep

**Result:**

Easier for front-end to track dsf changes.

---------

Co-authored-by: Michael <[email protected]>

Author: 2 people

src/contracts/core/DelegationManager.sol

@@ -474,7 +474,7 @@ contract DelegationManager is
         // Each of these operations fail if we attempt to remove more shares than exist
         for (uint256 i = 0; i < strategies.length; ++i) {
             IShareManager shareManager = _getShareManager(strategies[i]);
-            DepositScalingFactor memory dsf = _depositScalingFactor[staker][strategies[i]];
+            DepositScalingFactor storage dsf = _depositScalingFactor[staker][strategies[i]];
 
             // Calculate how many shares can be withdrawn after factoring in slashing
             withdrawableShares[i] = dsf.calcWithdrawable(depositSharesToWithdraw[i], slashingFactors[i]);
@@ -502,7 +502,8 @@ contract DelegationManager is
             uint256 sharesAfter = shareManager.removeDepositShares(staker, strategies[i], depositSharesToWithdraw[i]);
 
             if (sharesAfter == 0) {
-                _depositScalingFactor[staker][strategies[i]].reset();
+                dsf.reset();
+                emit DepositScalingFactorUpdated(staker, strategies[i], dsf.scalingFactor());
             }
         }
 

src/test/unit/DelegationUnit.t.sol

@@ -603,6 +603,8 @@ contract DelegationManagerUnitTests is EigenLayerUnitTestSetup, IDelegationManag
             cheats.expectEmit(true, true, true, true, address(delegationManager));
             emit OperatorSharesDecreased(params.operator, params.staker, params.strategy, params.operatorSharesDecreased);
             cheats.expectEmit(true, true, true, true, address(delegationManager));
+            emit DepositScalingFactorUpdated(params.staker, params.strategy, params.depositScalingFactor);
+            cheats.expectEmit(true, true, true, true, address(delegationManager));
             emit SlashingWithdrawalQueued(params.withdrawalRoot, params.withdrawal, params.operatorSharesDecreased.toArrayU256());
         }
     }