Fix stencil client serialization issue - #1147

Caused by: java.io.NotSerializableException: com.gojek.de.stencil.cache.DescriptorCacheLoader
Serialization stack:
	- object not serializable (class: com.gojek.de.stencil.cache.DescriptorCacheLoader, value: com.gojek.de.stencil.cache.DescriptorCacheLoader@5fb7af07)
	- field (class: com.gojek.de.stencil.client.URLStencilClient, name: cacheLoader, type: class com.gojek.de.stencil.cache.DescriptorCacheLoader)
	- object (class com.gojek.de.stencil.client.URLStencilClient, com.gojek.de.stencil.client.URLStencilClient@70c56f9d)
	- field (class: feast.ingestion.registry.proto.StencilProtoRegistry, name: stencilClient, type: interface com.gojek.de.stencil.client.StencilClient)
	- object (class feast.ingestion.registry.proto.StencilProtoRegistry, feast.ingestion.registry.proto.StencilProtoRegistry@35067eda)
	- element of array (index: 0)
	- array (class [Ljava.lang.Object;, size 2)
	- field (class: java.lang.invoke.SerializedLambda, name: capturedArgs, type: class [Ljava.lang.Object;)
	- object (class java.lang.invoke.SerializedLambda, SerializedLambda[capturingClass=class feast.ingestion.StreamingPipeline$, functionalInterfaceMethod=scala/Function1.apply:(Ljava/lang/Object;)Ljava/lang/Object;, implementation=invokeStatic feast/ingestion/StreamingPipeline$.$anonfun$protoParser$1:(Lfeast/ingestion/registry/proto/ProtoRegistry;Ljava/lang/String;[B)Lorg/apache/spark/sql/Row;, instantiatedMethodType=([B)Lorg/apache/spark/sql/Row;, numCaptured=2])
	- writeReplace data (class: java.lang.invoke.SerializedLambda)
	- object (class feast.ingestion.StreamingPipeline$$$Lambda$1473/1085738801, feast.ingestion.StreamingPipeline$$$Lambda$1473/1085738801@423c9375)
	- element of array (index: 3)
	- array (class [Ljava.lang.Object;, size 10)
	- element of array (index: 1)
	- array (class [Ljava.lang.Object;, size 3)
	- field (class: java.lang.invoke.SerializedLambda, name: capturedArgs, type: class [Ljava.lang.Object;)
	- object (class java.lang.invoke.SerializedLambda, SerializedLambda[capturingClass=class org.apache.spark.sql.execution.WholeStageCodegenExec, functionalInterfaceMethod=scala/Function2.apply:(Ljava/lang/Object;Ljava/lang/Object;)Ljava/lang/Object;, implementation=invokeStatic org/apache/spark/sql/execution/WholeStageCodegenExec.$anonfun$doExecute$4$adapted:(Lorg/apache/spark/sql/catalyst/expressions/codegen/CodeAndComment;[Ljava/lang/Object;Lorg/apache/spark/sql/execution/metric/SQLMetric;Ljava/lang/Object;Lscala/collection/Iterator;)Lscala/collection/Iterator;, instantiatedMethodType=(Ljava/lang/Object;Lscala/collection/Iterator;)Lscala/collection/Iterator;, numCaptured=3])
	- writeReplace data (class: java.lang.invoke.SerializedLambda)
	- object (class org.apache.spark.sql.execution.WholeStageCodegenExec$$Lambda$2182/174006344, org.apache.spark.sql.execution.WholeStageCodegenExec$$Lambda$2182/174006344@74f95597)
	at org.apache.spark.serializer.SerializationDebugger$.improveException(SerializationDebugger.scala:41)
	at org.apache.spark.serializer.JavaSerializationStream.writeObject(JavaSerializer.scala:46)
	at org.apache.spark.serializer.JavaSerializerInstance.serialize(JavaSerializer.scala:100)
	at org.apache.spark.util.ClosureCleaner$.ensureSerializable(ClosureCleaner.scala:413)