[#6623] fix(spark): Load JDBC driver explictly to fix No suitable driver found for mysql:xx error (#6673)

### What changes were proposed in this pull request?
If user set `spark.sql.hive.metastore.jars` to `path` in spark
configuration and hive metastore uri is not set explictly, Spark will
use Isolated client class loader to load JDBC drivers. which makes
Iceberg couldn't load corresponding class loader.

### Why are the changes needed?
Fix: #6623 

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

### How was this patch tested?
test locally

Co-authored-by: FANNG <xiaojing@datastrato.com>

Author: github-actions[bot]

spark-connector/spark-common/src/main/java/org/apache/gravitino/spark/connector/iceberg/GravitinoIcebergCatalog.java

@@ -22,6 +22,8 @@
 import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Method;
 import java.util.Map;
+import org.apache.commons.lang3.StringUtils;
+import org.apache.gravitino.catalog.lakehouse.iceberg.IcebergConstants;
 import org.apache.gravitino.catalog.lakehouse.iceberg.IcebergPropertiesUtils;
 import org.apache.gravitino.rel.Table;
 import org.apache.gravitino.spark.connector.PropertiesConverter;
@@ -58,6 +60,16 @@ public class GravitinoIcebergCatalog extends BaseCatalog
   @Override
   protected TableCatalog createAndInitSparkCatalog(
       String name, CaseInsensitiveStringMap options, Map<String, String> properties) {
+    String jdbcDriver = properties.get(IcebergConstants.GRAVITINO_JDBC_DRIVER);
+    if (StringUtils.isNotBlank(jdbcDriver)) {
+      // If `spark.sql.hive.metastore.jars` is set, Spark will use an isolated client class loader
+      // to load JDBC drivers, which makes Iceberg could not find corresponding JDBC driver.
+      try {
+        Class.forName(jdbcDriver);
+      } catch (Exception e) {
+        throw new RuntimeException(e);
+      }
+    }
     String catalogBackendName = IcebergPropertiesUtils.getCatalogBackendName(properties);
     Map<String, String> all =
         getPropertiesConverter().toSparkCatalogProperties(options, properties);