[SPARK-16530][SQL][TRIVIAL] Wrong Parser Keyword in ALTER TABLE CHANGE COLUMN

#### What changes were proposed in this pull request?
Based on the [Hive SQL syntax](https://cwiki.apache.org/confluence/display/Hive/LanguageManual+DDL#LanguageManualDDL-ChangeColumnName/Type/Position/Comment), the command to change column name/type/position/comment is `ALTER TABLE CHANGE COLUMN`. However, in our .g4 file, it is `ALTER TABLE CHANGE COLUMNS`. Because it is the last optional keyword, it does not take any effect. Thus, I put the issue as a Trivial level.

cc hvanhovell

#### How was this patch tested?
Existing test cases

Author: gatorsmile <gatorsmile@gmail.com>

Closes #14186 from gatorsmile/changeColumns.

sql/catalyst/src/main/antlr4/org/apache/spark/sql/catalyst/parser/SqlBase.g4

@@ -170,7 +170,7 @@ unsupportedHiveNativeCommands
     | kw1=ALTER kw2=TABLE tableIdentifier partitionSpec? kw3=CONCATENATE
     | kw1=ALTER kw2=TABLE tableIdentifier partitionSpec? kw3=SET kw4=FILEFORMAT
     | kw1=ALTER kw2=TABLE tableIdentifier partitionSpec? kw3=ADD kw4=COLUMNS
-    | kw1=ALTER kw2=TABLE tableIdentifier partitionSpec? kw3=CHANGE kw4=COLUMNS?
+    | kw1=ALTER kw2=TABLE tableIdentifier partitionSpec? kw3=CHANGE kw4=COLUMN?
     | kw1=ALTER kw2=TABLE tableIdentifier partitionSpec? kw3=REPLACE kw4=COLUMNS
     | kw1=START kw2=TRANSACTION
     | kw1=COMMIT