chore(dynamic sampling): emit a metric when boost_low_volume_projects_of_org was run successfully (#97671)

Author: shellmayr

src/sentry/dynamic_sampling/tasks/boost_low_volume_projects.py

@@ -283,6 +283,17 @@ def boost_low_volume_projects_of_org(
     )
     if rebalanced_projects is not None:
         store_rebalanced_projects(org_id, rebalanced_projects)
+        metrics.incr(
+            "dynamic_sampling.boost_low_volume_projects_of_org.success",
+            tags={"type": "rebalanced"},
+            sample_rate=1,
+        )
+    else:
+        metrics.incr(
+            "dynamic_sampling.boost_low_volume_projects_of_org.success",
+            tags={"type": "not_rebalanced"},
+            sample_rate=1,
+        )
 
 
 def fetch_projects_with_total_root_transaction_count_and_rates(