Update poolSize initial value to -1 (#6733)

* update poolSize initial value to -1

* Add generated changelog entries

---------

Co-authored-by: svc-changelog <svc-changelog@palantir.com>

Author: Slotermeyer

atlasdb-cassandra/src/main/java/com/palantir/atlasdb/keyvalue/cassandra/pool/CassandraClientPoolMetrics.java

@@ -43,7 +43,7 @@ public class CassandraClientPoolMetrics {
     // Not bundled in with request metrics, as we seek to not produce host-level metrics for economic reasons.
     private final Counter poolExhaustionCounter;
 
-    private final AtomicLong poolSize = new AtomicLong(0L);
+    private final AtomicLong poolSize = new AtomicLong(-1L);
 
     public CassandraClientPoolMetrics(MetricsManager metricsManager) {
         this.metricsManager = metricsManager;

changelog/@unreleased/pr-6733.v2.yml

@@ -0,0 +1,5 @@
+type: improvement
+improvement:
+  description: initialize pool size metric with value -1
+  links:
+  - https://github.com/palantir/atlasdb/pull/6733