Adapt JDBC tests to connect to default database

Before the network refactor, the requested database was ignored, so requesting
a non-existing database didn't lead to an error. This is why the tests
didn't fail before.

Author: tcm-marcel

script/testing/jdbc/src/PelotonErrorTest.java

@@ -23,7 +23,7 @@ public class PelotonErrorTest {
     private static final String DDL = "CREATE TABLE foo(id integer PRIMARY KEY, year integer);";
 
     private static Connection makeConnection(String host, int port, String username, String pass) throws SQLException {
-        String url = String.format("jdbc:postgresql://%s:%d/pavlo", host, port);
+        String url = String.format("jdbc:postgresql://%s:%d/default_database", host, port);
         Connection conn = DriverManager.getConnection(url, username, pass);
         return conn;
     }

script/testing/jdbc/src/PelotonTypeTest.java

@@ -34,7 +34,7 @@ public class PelotonTypeTest {
 
 
     private static Connection makeConnection(String host, int port, String username, String pass) throws SQLException {
-        String url = String.format("jdbc:postgresql://%s:%d/pavlo", host, port);
+        String url = String.format("jdbc:postgresql://%s:%d/default_database", host, port);
         Connection conn = DriverManager.getConnection(url, username, pass);
         return conn;
     }