Add new leaflet map background configuration #14863

Job	Run time
Set up docker build 'dynamic' env variables	1s
Build and check documentation	3m 31s
Run the Django test suite	8m 2s
End-to-end tests, chromium	17m 20s
End-to-end tests, firefox	19m 54s
Run the Django test suite in reverse	5m 56s
End-to-end tests, webkit	17m 31s
docker_build (production) / Build image	2m 45s
docker_build (extensions, token_exchange,prefill_haalcentraalhr, all-extensions-) / Build image	2m 47s
Scan docker image	2m 8s
Simulate upgrading instances (2.7.4)	1m 30s
Simulate upgrading instances (2.7.8)	1m 36s
Check for unexepected OAS changes	4s
Generate SDKs from OAS	39s
Validate OAS	14s
Generate Postman collection from OAS	11s
Push Docker image	0s
update-docker-readme	0s
	1h 24m 9s

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