Squash / clean up (old) migrations #14993

Job	Run time
Set up docker build 'dynamic' env variables	1s
Build and check documentation	3m 56s
End-to-end tests, chromium	13m 34s
Run the Django test suite	8m 45s
Run the Django test suite in reverse	5m 31s
End-to-end tests, firefox	16m 45s
End-to-end tests, webkit	12m 31s
docker_build (extensions, token_exchange,prefill_haalcentraalhr, all-extensions-) / Build image	2m 52s
docker_build (production) / Build image	2m 44s
Simulate upgrading instances (2.7.4)	1m 16s
Simulate upgrading instances (2.7.8)	1m 18s
Scan docker image	2m 4s
Check for unexepected OAS changes	5s
Validate OAS	16s
Generate SDKs from OAS	31s
Generate Postman collection from OAS	13s
Push Docker image	0s
update-docker-readme	0s
	1h 12m 22s

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