Downgrade Prometheus (v2.42.0 -> v2.41.0) until a container image gets published

Container image not published yet.

Reverts #2438

roles/custom/matrix-prometheus/defaults/main.yml

@@ -5,7 +5,7 @@
 
 matrix_prometheus_enabled: false
 
-matrix_prometheus_version: v2.42.0
+matrix_prometheus_version: v2.41.0
 matrix_prometheus_docker_image: "{{ matrix_container_global_registry_prefix }}prom/prometheus:{{ matrix_prometheus_version }}"
 matrix_prometheus_docker_image_force_pull: "{{ matrix_prometheus_docker_image.endswith(':latest') }}"