Serum: Don't attempt deactivating token positions after serum actions

While a serum open orders is active, the base and quote token positions
for it are locked to active. It's pointless to check if they need to be
deactivated after place/settle etc.

programs/mango-v4/src/instructions/serum3_liq_force_cancel_orders.rs

@@ -154,7 +154,6 @@ pub fn serum3_liq_force_cancel_orders(
         &ctx.accounts.account.key(),
         LoanOriginationFeeInstruction::Serum3LiqForceCancelOrders,
     );
-    difference_result.deactivate_inactive_token_accounts(&mut account.borrow_mut());
 
     Ok(())
 }

programs/mango-v4/src/instructions/serum3_place_order.rs

@@ -336,7 +336,6 @@ pub fn serum3_place_order(
         &ctx.accounts.account.key(),
         LoanOriginationFeeInstruction::Serum3PlaceOrder,
     );
-    vault_difference.deactivate_inactive_token_accounts(&mut account.borrow_mut());
 
     Ok(())
 }

programs/mango-v4/src/instructions/serum3_settle_funds.rs

@@ -169,7 +169,6 @@ pub fn serum3_settle_funds(ctx: Context<Serum3SettleFunds>) -> Result<()> {
             &ctx.accounts.account.key(),
             LoanOriginationFeeInstruction::Serum3SettleFunds,
         );
-        difference_result.deactivate_inactive_token_accounts(&mut account.borrow_mut());
     }
 
     Ok(())