Fix event and logging in unstake_from_subnet

Author: gztensor

pallets/subtensor/src/staking/stake_utils.rs

@@ -770,15 +770,15 @@ impl<T: Config> Pallet<T> {
             coldkey.clone(),
             hotkey.clone(),
             tao_unstaked,
-            alpha,
+            actual_alpha_decrease,
             netuid,
         ));
         log::info!(
             "StakeRemoved( coldkey: {:?}, hotkey:{:?}, tao: {:?}, alpha:{:?}, netuid: {:?} )",
             coldkey.clone(),
             hotkey.clone(),
             tao_unstaked,
-            alpha,
+            actual_alpha_decrease,
             netuid
         );