[SPARK-11191][SQL][FOLLOW-UP] Cleans up unnecessary anonymous HiveFunctionRegistry

According to discussion in PR #9664, the anonymous `HiveFunctionRegistry` in `HiveContext` can be removed now.

Author: Cheng Lian <lian@databricks.com>

Closes #9737 from liancheng/spark-11191.follow-up.

sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveContext.scala

@@ -454,15 +454,7 @@ class HiveContext private[hive](
   // Note that HiveUDFs will be overridden by functions registered in this context.
   @transient
   override protected[sql] lazy val functionRegistry: FunctionRegistry =
-    new HiveFunctionRegistry(FunctionRegistry.builtin.copy(), this) {
-      override def lookupFunction(name: String, children: Seq[Expression]): Expression = {
-        // Hive Registry need current database to lookup function
-        // TODO: the current database of executionHive should be consistent with metadataHive
-        executionHive.withHiveState {
-          super.lookupFunction(name, children)
-        }
-      }
-    }
+    new HiveFunctionRegistry(FunctionRegistry.builtin.copy(), this.executionHive)
 
   // The Hive UDF current_database() is foldable, will be evaluated by optimizer, but the optimizer
   // can't access the SessionState of metadataHive.

sql/hive/src/main/scala/org/apache/spark/sql/hive/hiveUDFs.scala

@@ -43,16 +43,19 @@ import org.apache.spark.sql.catalyst.plans.logical._
 import org.apache.spark.sql.catalyst.rules.Rule
 import org.apache.spark.sql.catalyst.util.ArrayData
 import org.apache.spark.sql.hive.HiveShim._
+import org.apache.spark.sql.hive.client.ClientWrapper
 import org.apache.spark.sql.types._
 
 
 private[hive] class HiveFunctionRegistry(
     underlying: analysis.FunctionRegistry,
-    hiveContext: HiveContext)
+    executionHive: ClientWrapper)
   extends analysis.FunctionRegistry with HiveInspectors {
 
   def getFunctionInfo(name: String): FunctionInfo = {
-    hiveContext.executionHive.withHiveState {
+    // Hive Registry need current database to lookup function
+    // TODO: the current database of executionHive should be consistent with metadataHive
+    executionHive.withHiveState {
       FunctionRegistry.getFunctionInfo(name)
     }
   }