[SPARK-34153][SQL] Remove unused getRawTable() from HiveExternalCatalog.alterPartitions()

### What changes were proposed in this pull request?
Remove unused call of `getRawTable()` from `HiveExternalCatalog.alterPartitions()`.

### Why are the changes needed?
It reduces the number of calls to Hive External catalog.

### Does this PR introduce _any_ user-facing change?
No

### How was this patch tested?
By running the modified test suite:
```
$ build/sbt -Phive-2.3 -Phive-thriftserver "test:testOnly *AlterTableRenamePartitionSuite"
```

Closes #31234 from MaxGekk/remove-getRawTable-from-alterPartitions.

Authored-by: Max Gekk <max.gekk@gmail.com>
Signed-off-by: HyukjinKwon <gurwls223@apache.org>

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

@@ -1144,9 +1144,6 @@ private[spark] class HiveExternalCatalog(conf: SparkConf, hadoopConf: Configurat
       table: String,
       newParts: Seq[CatalogTablePartition]): Unit = withClient {
     val metaStoreParts = newParts.map(p => p.copy(spec = toMetaStorePartitionSpec(p.spec)))
-
-    val rawTable = getRawTable(db, table)
-
     // convert partition statistics to properties so that we can persist them through hive api
     val withStatsProps = metaStoreParts.map { p =>
       if (p.stats.isDefined) {

sql/hive/src/test/scala/org/apache/spark/sql/hive/execution/command/AlterTableRenamePartitionSuite.scala

@@ -40,5 +40,13 @@ class AlterTableRenamePartitionSuite
         sql(s"ALTER TABLE $t PARTITION (part=1) RENAME TO PARTITION (part=2)")
       }
     }
+
+    withNamespaceAndTable("ns", "tbl") { t =>
+      sql(s"CREATE TABLE $t (id int, PART int) $defaultUsing PARTITIONED BY (PART)")
+      sql(s"INSERT INTO $t PARTITION (PART=0) SELECT 0")
+      checkHiveClientCalls(expected = 26) {
+        sql(s"ALTER TABLE $t PARTITION (PART=0) RENAME TO PARTITION (PART=1)")
+      }
+    }
   }
 }