Reduce MEV Blocker refunds test logs (#114)

Noticed that the threshold is relatively high for alerts, given the
current value of ETH. Also noticed that we get a lot of meaningless logs
so decided to reduce those as well.


![image](https://github.com/user-attachments/assets/73300479-2024-474c-920e-4d385321816c)

src/monitoring_tests/mev_blocker_kickbacks_test.py

@@ -53,5 +53,6 @@ def run(self, tx_hash: str) -> bool:
         if eth_kickbacks >= KICKBACKS_ALERT_THRESHOLD:
             self.alert(log_output)
         else:
-            self.logger.info(log_output)
+            if eth_kickbacks > 0:
+                self.logger.info(log_output)
         return True