[DISCO-4025] fix: fetch engagement metric default (#1360)

Author: tiftran

merino/providers/suggest/adm/provider.py

@@ -214,7 +214,7 @@ def _fetch_engagement_metrics(self, suggestion: PyAmpResult) -> EngagementMetric
         engaged, attempted = 1, 1
         if self.engagement_data and (metrics := self.engagement_data.amp.get(advertiser)):
             attempted = int(metrics.get("impressions", attempted))
-            engaged = int(metrics.get("clicks", attempted))
+            engaged = int(metrics.get("clicks", engaged))
         return EngagementMetrics(engaged=engaged, attempted=attempted)
 
     def _is_thompson_eligible(self, client_variants: list[str]) -> bool: