[Improve] Enhance MySQL data source configuration and error handling (#299)

Author: zhangshenghang

seatunnel-datasource/seatunnel-datasource-plugins/datasource-jdbc-mysql/src/main/java/org/apache/seatunnel/datasource/plugin/mysql/jdbc/MysqlDataSourceConfig.java

@@ -42,8 +42,11 @@ public class MysqlDataSourceConfig {
 
     public static final OptionRule OPTION_RULE =
             OptionRule.builder()
-                    .required(MysqlOptionRule.URL, MysqlOptionRule.DRIVER)
-                    .optional(MysqlOptionRule.USER, MysqlOptionRule.PASSWORD)
+                    .required(
+                            MysqlOptionRule.URL,
+                            MysqlOptionRule.DRIVER,
+                            MysqlOptionRule.USER,
+                            MysqlOptionRule.PASSWORD)
                     .build();
 
     public static final OptionRule METADATA_RULE =

seatunnel-datasource/seatunnel-datasource-plugins/datasource-jdbc-mysql/src/main/java/org/apache/seatunnel/datasource/plugin/mysql/jdbc/MysqlJdbcDataSourceChannel.java

@@ -116,7 +116,7 @@ public boolean checkDataSourceConnectivity(
         try (Connection ignored = getConnection(requestParams)) {
             return true;
         } catch (Exception e) {
-            throw new DataSourcePluginException("check jdbc connectivity failed", e);
+            throw new DataSourcePluginException(e.getMessage(), e);
         }
     }