[SPARK-39656][SQL][3.2] Fix wrong namespace in DescribeNamespaceExec

backport #37049 for branch-3.2
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DescribeNamespaceExec change ns.last to ns.quoted

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DescribeNamespaceExec should show the whole namespace rather than last

### Does this PR introduce _any_ user-facing change?
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yes, a small bug fix

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fix test

Closes #37072 from ulysses-you/desc-namespace-3.2.

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

Author: ulysses-you

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/connector/DataSourceV2SQLSuite.scala

@@ -1243,7 +1243,7 @@ class DataSourceV2SQLSuite
         ))
       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, "/tmp/ns_test"),
         Row(SupportsNamespaces.PROP_OWNER.capitalize, defaultUser))
@@ -1258,7 +1258,7 @@ class DataSourceV2SQLSuite
       sql("ALTER NAMESPACE testcat.ns1.ns2 SET PROPERTIES ('a'='b','b'='a')")
       val descriptionDf = sql("DESCRIBE NAMESPACE EXTENDED testcat.ns1.ns2")
       assert(descriptionDf.collect() === Seq(
-        Row("Namespace Name", "ns2"),
+        Row("Namespace Name", "ns1.ns2"),
         Row(SupportsNamespaces.PROP_COMMENT.capitalize, "test namespace"),
         Row(SupportsNamespaces.PROP_LOCATION.capitalize, "/tmp/ns_test"),
         Row(SupportsNamespaces.PROP_OWNER.capitalize, defaultUser),
@@ -1305,7 +1305,7 @@ class DataSourceV2SQLSuite
       sql("ALTER NAMESPACE testcat.ns1.ns2 SET LOCATION '/tmp/ns_test_2'")
       val descriptionDf = sql("DESCRIBE NAMESPACE EXTENDED testcat.ns1.ns2")
       assert(descriptionDf.collect() === Seq(
-        Row("Namespace Name", "ns2"),
+        Row("Namespace Name", "ns1.ns2"),
         Row(SupportsNamespaces.PROP_COMMENT.capitalize, "test namespace"),
         Row(SupportsNamespaces.PROP_LOCATION.capitalize, "/tmp/ns_test_2"),
         Row(SupportsNamespaces.PROP_OWNER.capitalize, defaultUser))