Rework OpenID Connect integration #12604

Job	Run time
Set up docker build 'dynamic' env variables	1s
Build and check documentation	1m 53s
End-to-end tests, chromium	2m 56s
Run the Django test suite	3m 41s
End-to-end tests, firefox	4m 49s
End-to-end tests, webkit	3m 35s
Run the Django test suite in reverse	3m 33s
docker_build (extensions, token_exchange,prefill_haalcentraalhr, all-extensions-) / Build image	4m 12s
docker_build (production) / Build image	4m 19s
Check for unexepected OAS changes	0s
Generate Postman collection from OAS	0s
Generate SDKs from OAS	0s
Validate OAS	0s
Scan docker image	0s
Push Docker image	0s
update-docker-readme	0s
	28m 59s

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