chore: upgrade mariadb image (#5584)

# Why

Dependabot/renovate PRs have e2e test failures due to missing image:
`Failed to pull image "docker.io/bitnami/mariadb:10.11.4-debian-11-r0":
rpc error: code = NotFound desc = failed to pull and unpack image
"docker.io/bitnami/mariadb:10.11.4-debian-11-r0": failed to resolve
reference "docker.io/bitnami/mariadb:10.11.4-debian-11-r0"`

# What

Upgrades Mariadb to a more recent version.

Author: mthorning

helm/oncall/Chart.lock

@@ -0,0 +1,27 @@
+dependencies:
+- name: cert-manager
+  repository: https://charts.jetstack.io
+  version: v1.8.0
+- name: mariadb
+  repository: https://charts.bitnami.com/bitnami
+  version: 23.2.1
+- name: postgresql
+  repository: https://charts.bitnami.com/bitnami
+  version: 11.9.10
+- name: rabbitmq
+  repository: https://charts.bitnami.com/bitnami
+  version: 12.0.0
+- name: redis
+  repository: https://charts.bitnami.com/bitnami
+  version: 16.13.2
+- name: grafana
+  repository: https://grafana.github.io/helm-charts
+  version: 8.4.6
+- name: ingress-nginx
+  repository: https://kubernetes.github.io/ingress-nginx
+  version: 4.1.4
+- name: prometheus
+  repository: https://prometheus-community.github.io/helm-charts
+  version: 25.8.2
+digest: sha256:afc88eda236fdd89ae79854d5fba902f7cda52ea640df123f30d9e5d9698d128
+generated: "2025-10-24T11:19:37.530187+01:00"

helm/oncall/Chart.yaml

@@ -10,7 +10,7 @@ dependencies:
     repository: https://charts.jetstack.io
     condition: cert-manager.enabled
   - name: mariadb
-    version: 12.2.5
+    version: 23.2.1
     repository: https://charts.bitnami.com/bitnami
     condition: mariadb.enabled
   - name: postgresql