[SPARK-29675][SQL] Add exception when isolationLevel is Illegal

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

Now we use JDBC api and set an Illegal isolationLevel option, spark will throw a `scala.MatchError`, it's not friendly to user. So we should add an IllegalArgumentException.

### Why are the changes needed?

Make exception friendly to user.

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

No.

### How was this patch tested?

Add UT.

Closes #26334 from ulysses-you/SPARK-29675.

Authored-by: ulysses <youxiduo@weidian.com>
Signed-off-by: Dongjoon Hyun <dhyun@apple.com>

sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/jdbc/JDBCOptions.scala

@@ -177,6 +177,10 @@ class JDBCOptions(
       case "READ_COMMITTED" => Connection.TRANSACTION_READ_COMMITTED
       case "REPEATABLE_READ" => Connection.TRANSACTION_REPEATABLE_READ
       case "SERIALIZABLE" => Connection.TRANSACTION_SERIALIZABLE
+      case other => throw new IllegalArgumentException(
+        s"Invalid value `$other` for parameter `$JDBC_TXN_ISOLATION_LEVEL`. This can be " +
+          "`NONE`, `READ_UNCOMMITTED`, `READ_COMMITTED`, `REPEATABLE_READ` or `SERIALIZABLE`."
+      )
     }
   // An option to execute custom SQL before fetching data from the remote DB
   val sessionInitStatement = parameters.get(JDBC_SESSION_INIT_STATEMENT)

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

@@ -1649,4 +1649,17 @@ class JDBCSuite extends QueryTest
       }
     }
   }
+
+  test("Add exception when isolationLevel is Illegal") {
+    val e = intercept[IllegalArgumentException] {
+      spark.read.format("jdbc")
+        .option("Url", urlWithUserAndPass)
+        .option("dbTable", "test.people")
+        .option("isolationLevel", "test")
+        .load()
+    }.getMessage
+    assert(e.contains(
+      "Invalid value `test` for parameter `isolationLevel`. This can be " +
+      "`NONE`, `READ_UNCOMMITTED`, `READ_COMMITTED`, `REPEATABLE_READ` or `SERIALIZABLE`."))
+  }
 }