[FLINK-20540][jdbc] Fix JdbcCatalog connection exception when baseUrl doesn't end with slash

This closes #14362
Co-authored-by: Nzhao.zhang <zhao.zhang@upai.com>

flink-connectors/flink-connector-jdbc/src/main/java/org/apache/flink/connector/jdbc/catalog/AbstractJdbcCatalog.java

@@ -88,7 +88,7 @@ public abstract class AbstractJdbcCatalog extends AbstractCatalog {
 		this.username = username;
 		this.pwd = pwd;
 		this.baseUrl = baseUrl.endsWith("/") ? baseUrl : baseUrl + "/";
-		this.defaultUrl = baseUrl + defaultDatabase;
+		this.defaultUrl = this.baseUrl + defaultDatabase;
 	}
 
 	@Override

flink-connectors/flink-connector-jdbc/src/test/java/org/apache/flink/connector/jdbc/catalog/PostgresCatalogTestBase.java

@@ -68,7 +68,7 @@ public class PostgresCatalogTestBase {
 		// jdbc:postgresql://localhost:50807/postgres?user=postgres
 		String embeddedJdbcUrl = pg.getEmbeddedPostgres().getJdbcUrl(TEST_USERNAME, TEST_PWD);
 		// jdbc:postgresql://localhost:50807/
-		baseUrl = embeddedJdbcUrl.substring(0, embeddedJdbcUrl.lastIndexOf("/") + 1);
+		baseUrl = embeddedJdbcUrl.substring(0, embeddedJdbcUrl.lastIndexOf("/"));
 
 		catalog = new PostgresCatalog(TEST_CATALOG_NAME, PostgresCatalog.DEFAULT_DATABASE, TEST_USERNAME, TEST_PWD, baseUrl);
 
@@ -122,7 +122,7 @@ public class PostgresCatalogTestBase {
 	}
 
 	public static void executeSQL(String db, String sql) throws SQLException {
-		try (Connection conn = DriverManager.getConnection(baseUrl + db, TEST_USERNAME, TEST_PWD);
+		try (Connection conn = DriverManager.getConnection(String.format("%s/%s", baseUrl, db), TEST_USERNAME, TEST_PWD);
 			Statement statement = conn.createStatement()) {
 			statement.executeUpdate(sql);
 		} catch (SQLException e) {