Fix postgres migration test failure

Using `CREATE INDEX CONCURRENTLY` in our new migration causes flyway to
automatically run the migration in `autocommit` mode.
`connection.commit()` is only supposed to be called when autocommit mode
is off.

This change makes our migration test runner able to handle migrations
that run in `autocommit` mode.

[#169775896]

Signed-off-by: Andrew Edstrom <aedstrom@pivotal.io>
Co-authored-by: Andrew Edstrom <aedstrom@pivotal.io>
Signed-off-by: Andrew Edstrom <aedstrom@pivotal.io>

server/src/test/java/org/cloudfoundry/identity/uaa/db/MigrationTestRunner.java

@@ -25,7 +25,9 @@ public void run(MigrationTest... tests) {
             public void afterEachMigrate(Connection connection, MigrationInfo info) {
                 super.afterEachMigrate(connection, info);
                 try {
-                    connection.commit();
+                    if (!connection.getAutoCommit()) {
+                        connection.commit();
+                    }
                 } catch (SQLException e) {
                     Assert.fail(e.getMessage());
                 }