[SPARK-39656][SQL][3.3] Fix wrong namespace in DescribeNamespaceExec

backport #37049 for branch-3.3

### What changes were proposed in this pull request?

DescribeNamespaceExec change ns.last to ns.quoted

### Why are the changes needed?

DescribeNamespaceExec should show the whole namespace rather than last

### Does this PR introduce _any_ user-facing change?

yes, a small bug fix

### How was this patch tested?

fix test

Closes #37071 from ulysses-you/desc-namespace-3.3.

Authored-by: ulysses-you <ulyssesyou18@gmail.com>
Signed-off-by: huaxingao <huaxin_gao@apple.com>

sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/v2/DescribeNamespaceExec.scala

@@ -23,6 +23,7 @@ import scala.collection.mutable.ArrayBuffer
 import org.apache.spark.sql.catalyst.InternalRow
 import org.apache.spark.sql.catalyst.expressions.Attribute
 import org.apache.spark.sql.connector.catalog.{CatalogV2Util, SupportsNamespaces}
+import org.apache.spark.sql.connector.catalog.CatalogV2Implicits._
 
 /**
  * Physical plan node for describing a namespace.
@@ -37,7 +38,7 @@ case class DescribeNamespaceExec(
     val ns = namespace.toArray
     val metadata = catalog.loadNamespaceMetadata(ns)
 
-    rows += toCatalystRow("Namespace Name", ns.last)
+    rows += toCatalystRow("Namespace Name", ns.quoted)
 
     CatalogV2Util.NAMESPACE_RESERVED_PROPERTIES.foreach { p =>
       rows ++= Option(metadata.get(p)).map(toCatalystRow(p.capitalize, _))

sql/core/src/test/scala/org/apache/spark/sql/execution/command/v2/DescribeNamespaceSuite.scala

@@ -41,7 +41,7 @@ class DescribeNamespaceSuite extends command.DescribeNamespaceSuiteBase with Com
         ))
       val description = descriptionDf.collect()
       assert(description === Seq(
-        Row("Namespace Name", "ns2"),
+        Row("Namespace Name", "ns1.ns2"),
         Row(SupportsNamespaces.PROP_COMMENT.capitalize, "test namespace"),
         Row(SupportsNamespaces.PROP_LOCATION.capitalize, "file:/tmp/ns_test"),
         Row(SupportsNamespaces.PROP_OWNER.capitalize, Utils.getCurrentUserName()))