Add new leaflet map background configuration #14765

Job	Run time
Set up docker build 'dynamic' env variables	1s
Run the Django test suite	3m 30s
Build and check documentation	3m 46s
End-to-end tests, chromium	2m 40s
Run the Django test suite in reverse	3m 12s
End-to-end tests, firefox	2m 42s
End-to-end tests, webkit	2m 50s
docker_build (extensions, token_exchange,prefill_haalcentraalhr, all-extensions-) / Build image	2m 48s
docker_build (production) / Build image	2m 46s
Scan docker image	2m 6s
Simulate upgrading instances (2.7.4)	1m 14s
Simulate upgrading instances (2.7.8)	1m 17s
Check for unexepected OAS changes	0s
Generate Postman collection from OAS	0s
Validate OAS	0s
Generate SDKs from OAS	0s
Push Docker image	0s
update-docker-readme	0s
	28m 52s

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