Removed the default values of pool status

Author: Zhen

driver/src/main/java/org/neo4j/driver/internal/metrics/spi/PoolStatus.java

@@ -20,18 +20,5 @@
 
 public enum PoolStatus
 {
-    OPEN( 0 ),
-    CLOSED( 1 );
-
-    private final int value;
-
-    PoolStatus( int value )
-    {
-        this.value = value;
-    }
-
-    public int value()
-    {
-        return value;
-    }
+    OPEN, CLOSED
 }