[SDFAB-612] Cluster not ready when using recent tost master images

Initialize the local cache before adding the map listener
to prevent npe which are caused by events delivered during
the bootstrap process of the EC map

Change-Id: I823c12ccaa633a11a10d5b5d5fa7250a078ff4c5
(cherry picked from commit ec0e942320ef27932b4173172055151015261d7c)
diff --git a/core/store/dist/src/main/java/org/onosproject/store/meter/impl/DistributedMeterStore.java b/core/store/dist/src/main/java/org/onosproject/store/meter/impl/DistributedMeterStore.java
index b94375c..30da74d 100644
--- a/core/store/dist/src/main/java/org/onosproject/store/meter/impl/DistributedMeterStore.java
+++ b/core/store/dist/src/main/java/org/onosproject/store/meter/impl/DistributedMeterStore.java
@@ -114,7 +114,8 @@
 
     // Meters id related objects
     private static final String AVAILABLEMETERIDSTORE = "onos-meters-available-store";
-    protected ConcurrentMap<MeterTableKey, DistributedSet<MeterKey>> availableMeterIds;
+    protected final ConcurrentMap<MeterTableKey, DistributedSet<MeterKey>> availableMeterIds =
+            new ConcurrentHashMap<>();
     private static final String METERIDSTORE = "onos-meters-id-store";
     private AtomicCounterMap<MeterTableKey> meterIdGenerators;
 
@@ -177,8 +178,6 @@
                 .withSerializer(APP_KRYO_BUILDER).build();
         metersFeatures.addListener(featuresMapListener);
 
-        availableMeterIds = new ConcurrentHashMap<>();
-
         meterIdGenerators = storageService.<MeterTableKey>atomicCounterMapBuilder()
                 .withName(METERIDSTORE)
                 .withSerializer(Serializer.using(KryoNamespaces.API,