notifications-controller doesn't trust certs from argocd-tls-certs-cm configmap

[svghadi]

Describe the bug
notifications-controller doesn't trust custom certs added into argocd-tls-certs-cm causing failures to send notifications to webhook endpoints with self-signed/custom certificates.

To Reproduce

1. Configure notification in argocd-notifications-cm

   apiVersion: v1
   kind: ConfigMap
   metadata:
     name: argocd-notifications-cm
   data:
     service.webhook.display: |-
       url: https://<endpoint-with-custom-cert>
     trigger.on-created: |-
       - description: Application is created.
         oncePer: app.metadata.name
         send:
         - app-created
         when: "true"

2. Add custom tls cert in argocd-tls-certs-cm
3. Restart the notifications-controller deployment
4. Create an application with following annotation

   annotations:
     notifications.argoproj.io/subscribe.on-created.display: ""

5. Check notifications-controller deployment for tls: failed to verify certificate: x509

Expected behavior

notifications-controller should send notifications successfully to endpoint by trusting custom certs from argocd-tls-certs-cm configmap

Version

latest/master

Logs

time="2023-09-07T05:01:49Z" level=info msg="Start processing" resource=argocd-e2e/new-app
time="2023-09-07T05:01:49Z" level=info msg="Trigger on-created result: [{[0].X_5TO4MPCKAyY0ipFgr6_IraRNs new-app [app-created] true}]" resource=argocd-e2e/new-app
time="2023-09-07T05:01:49Z" level=info msg="Sending notification about condition 'on-created.[0].X_5TO4MPCKAyY0ipFgr6_IraRNs' to '{display }' using the configuration in namespace argocd-e2e" resource=argocd-e2e/new-app
time="2023-09-07T05:01:49Z" level=error msg="Failed to notify recipient {display } defined in resource argocd-e2e/new-app: Get \"https://endpoint.webhook/hooks/display\": tls: failed to verify certificate: x509: certificate signed by unknown authority using the configuration in namespace argocd-e2e" resource=argocd-e2e/new-app
time="2023-09-07T05:01:49Z" level=info msg="Processing completed" resource=argocd-e2e/new-app

Additional Info
The certs from argocd-tls-certs-cm are correctly mounted into notifications-controller pod at /app/config/tls path however seems like controller is not reading them.