[SPARK-51022][SQL] Remove unused tableSampleClause in build() met…

…hod of `MsSqlServerSQLQueryBuilder` and `DB2SQLQueryBuilder`

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

This PR aims to remove unused `tableSampleClause` in `build()` method of `MsSqlServerSQLQueryBuilder` and `DB2SQLBuilder`.

From the discussion here: apache#49711 (comment)

### Why are the changes needed?

Currently, `MsSqlServerDialect` and `DB2Dialect` don't support `tableSample` (default value of `supportsTableSample` is `false`), so `tableSampleClause` is unnecessary when building sql in the `build()` method.

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

No.

### How was this patch tested?

Updated a  related test case and passed GA.

### Was this patch authored or co-authored using generative AI tooling?

No.

Closes apache#49714 from wayneguow/jdbc_tablesample.

Authored-by: Wei Guo <guow93@gmail.com>
Signed-off-by: beliefer <beliefer@163.com>

connector/docker-integration-tests/src/test/scala/org/apache/spark/sql/jdbc/v2/MsSqlServerIntegrationSuite.scala

@@ -171,7 +171,7 @@ class MsSqlServerIntegrationSuite extends DockerJDBCIntegrationV2Suite with V2JD
 
     // scalastyle:off
     assert(getExternalEngineQuery(df.queryExecution.executedPlan) ==
-      """SELECT  "dept","name","salary","bonus" FROM "employee"  WHERE (CASE WHEN ("name" = 'Legolas') THEN IIF(("name" = 'Elf'), 1, 0) ELSE IIF(("name" <> 'Wizard'), 1, 0) END = 1)  """
+      """SELECT  "dept","name","salary","bonus" FROM "employee" WHERE (CASE WHEN ("name" = 'Legolas') THEN IIF(("name" = 'Elf'), 1, 0) ELSE IIF(("name" <> 'Wizard'), 1, 0) END = 1)  """
     )
     // scalastyle:on
     df.collect()
@@ -186,7 +186,7 @@ class MsSqlServerIntegrationSuite extends DockerJDBCIntegrationV2Suite with V2JD
 
     // scalastyle:off
     assert(getExternalEngineQuery(df.queryExecution.executedPlan) ==
-      """SELECT  "dept","name","salary","bonus" FROM "employee"  WHERE (CASE WHEN ("name" = 'Legolas') THEN IIF(("name" = 'Elf'), 1, 0) ELSE 1 END = 1)  """
+      """SELECT  "dept","name","salary","bonus" FROM "employee" WHERE (CASE WHEN ("name" = 'Legolas') THEN IIF(("name" = 'Elf'), 1, 0) ELSE 1 END = 1)  """
     )
     // scalastyle:on
     df.collect()
@@ -203,7 +203,7 @@ class MsSqlServerIntegrationSuite extends DockerJDBCIntegrationV2Suite with V2JD
 
     // scalastyle:off
     assert(getExternalEngineQuery(df.queryExecution.executedPlan) ==
-      """SELECT  "dept","name","salary","bonus" FROM "employee"  WHERE (CASE WHEN ("name" = 'Legolas') THEN IIF((CASE WHEN ("name" = 'Elf') THEN IIF(("name" = 'Elrond'), 1, 0) ELSE IIF(("name" = 'Gandalf'), 1, 0) END = 1), 1, 0) ELSE IIF(("name" = 'Sauron'), 1, 0) END = 1)  """
+      """SELECT  "dept","name","salary","bonus" FROM "employee" WHERE (CASE WHEN ("name" = 'Legolas') THEN IIF((CASE WHEN ("name" = 'Elf') THEN IIF(("name" = 'Elrond'), 1, 0) ELSE IIF(("name" = 'Gandalf'), 1, 0) END = 1), 1, 0) ELSE IIF(("name" = 'Sauron'), 1, 0) END = 1)  """
     )
     // scalastyle:on
     df.collect()
@@ -220,7 +220,7 @@ class MsSqlServerIntegrationSuite extends DockerJDBCIntegrationV2Suite with V2JD
 
     // scalastyle:off
     assert(getExternalEngineQuery(df.queryExecution.executedPlan) ==
-      """SELECT  "dept","name","salary","bonus" FROM "employee"  WHERE ("name" IS NOT NULL) AND ((CASE WHEN "name" = 'Legolas' THEN CASE WHEN "name" = 'Elf' THEN 'Elf' ELSE 'Wizard' END ELSE 'Sauron' END) = "name")  """
+      """SELECT  "dept","name","salary","bonus" FROM "employee" WHERE ("name" IS NOT NULL) AND ((CASE WHEN "name" = 'Legolas' THEN CASE WHEN "name" = 'Elf' THEN 'Elf' ELSE 'Wizard' END ELSE 'Sauron' END) = "name")  """
     )
     // scalastyle:on
     df.collect()

sql/core/src/main/scala/org/apache/spark/sql/jdbc/DB2Dialect.scala

@@ -207,7 +207,7 @@ private case class DB2Dialect() extends JdbcDialect with SQLConfHelper with NoLe
       val offsetClause = dialect.getOffsetClause(offset)
 
       options.prepareQuery +
-        s"SELECT $columnList FROM ${options.tableOrQuery} $tableSampleClause" +
+        s"SELECT $columnList FROM ${options.tableOrQuery}" +
         s" $whereClause $groupByClause $orderByClause $offsetClause $limitClause"
     }
   }

sql/core/src/main/scala/org/apache/spark/sql/jdbc/MsSqlServerDialect.scala

@@ -250,7 +250,7 @@ private case class MsSqlServerDialect() extends JdbcDialect with NoLegacyJDBCErr
 
       options.prepareQuery +
         s"SELECT $limitClause $columnList FROM ${options.tableOrQuery}" +
-        s" $tableSampleClause $whereClause $groupByClause $orderByClause"
+        s" $whereClause $groupByClause $orderByClause"
     }
   }
 

sql/core/src/test/scala/org/apache/spark/sql/jdbc/JDBCSuite.scala

@@ -1107,7 +1107,7 @@ class JDBCSuite extends QueryTest with SharedSparkSession {
         .withLimit(123)
         .build()
         .trim() ==
-      "SELECT a,b FROM test      FETCH FIRST 123 ROWS ONLY")
+      "SELECT a,b FROM test     FETCH FIRST 123 ROWS ONLY")
   }
 
   test("table exists query by jdbc dialect") {