Add API endpoint for default fixed metadata variables of JSON dump plugin #15497

Job	Run time
Set up docker build 'dynamic' env variables	1s
Build and check documentation	1m 43s
End-to-end tests, chromium	14m 13s
End-to-end tests, firefox	18m 28s
Run the Django test suite	7m 35s
End-to-end tests, webkit	14m 5s
Run the Django test suite in reverse	5m 38s
docker_build (production) / Build image	2m 49s
docker_build (extensions, token_exchange,prefill_haalcentraalhr, all-extensions-) / Build image	2m 47s
Scan docker image	2m 51s
Simulate upgrading instances (3.0.1)	1m 30s
Check for unexepected OAS changes	5s
Validate OAS	13s
Generate SDKs from OAS	30s
Generate Postman collection from OAS	8s
Push Docker image	0s
update-docker-readme	0s
	1h 12m 36s

Provide feedback