remove jetstream leak

Change-Id: I46cf492d6285260f9e40fb2128f9cd5ad1624ca5

Author: igorbernstein2

google-cloud-bigtable/src/main/java/com/google/cloud/bigtable/data/v2/internal/csm/metrics/Constants.java

@@ -61,14 +61,6 @@ private MetricLabels() {}
     static final AttributeKey<String> DP_REASON_KEY = AttributeKey.stringKey("reason");
     static final AttributeKey<String> DP_IP_PREFERENCE_KEY = AttributeKey.stringKey("reason");
 
-    static final AttributeKey<String> SESSION_TYPE_KEY = AttributeKey.stringKey("session_type");
-    static final AttributeKey<String> SESSION_NAME = AttributeKey.stringKey("session_name");
-    static final AttributeKey<String> AFE_LOCATION_KEY = AttributeKey.stringKey("afe_location");
-
-    static final AttributeKey<String> REASON_KEY = AttributeKey.stringKey("closing_reason");
-    static final AttributeKey<String> VRPCS_KEY = AttributeKey.stringKey("vrpcs");
-    static final AttributeKey<Boolean> SESSION_READY_KEY = AttributeKey.booleanKey("ready");
-
     public static final AttributeKey<String> STATUS_KEY = AttributeKey.stringKey("status");
 
     static final AttributeKey<String> EXECUTOR_KEY = AttributeKey.stringKey("executor");