Remove unused variable from pg connector manager. Closes #1140

lib/dialects/postgres/connector-manager.js

@@ -12,7 +12,6 @@ module.exports = (function() {
     this.config.port    = this.config.port || 5432
     this.pooling        = (!!this.config.pool && (this.config.pool.maxConnections > 0))
     this.pg             = this.config.native ? require(pgModule).native : require(pgModule)
-    this.poolIdentifier = null
     // Better support for BigInts
     // https://github.com/brianc/node-postgres/issues/166#issuecomment-9514935
     this.pg.types.setTypeParser(20, String);
@@ -181,10 +180,6 @@ module.exports = (function() {
   }
 
   ConnectorManager.prototype.disconnect = function() {
-    if (this.poolIdentifier) {
-      this.poolIdentifier.destroyAllNow()
-    }
-
     if (this.client) {
       if (this.clientDrained) {
         this.client.end()