Dockerfile for idp test app not using correct paths

[lullis]

Describe the bug

When building the idp/rdp test apps, the idp server fails when initiating login, as it can not find the registration/login.html template.

To Reproduce

• Run docker-compose up -d --build to build the docker image and start the services.
• Go to the rdp app (localhost:5173)
• Click "login"
• Results in Server Error

Expected behavior

• The server should be able to find the login template and render the page properly.

Version

• I have tested with the latest published release and it's still a problem.
• I have tested with the master branch and it's still a problem.

Additional context
Is this "tests project" meant only for testing, or could/should it be used for development as well? It looks like no one is actually using during development (otherwise other people would spot these glaring errors), so perhaps I shouldn't be spending so much time in order to get this going.

[dopry]

@lullis The compose environment is meant for testing. We plan to setup playwright for end to end testing with it. We also intend to distribute the IDP image at some point in the future for people who want to stand up an IDP in their own container environment.

I opened #1550 with a more focused fix than the changes you proposed in #1549. Can you give it a go and let me if it resolves the issue you were having?