chore(RELEASE-2170): remove signing configmaps in stage (redhat-appstudio#423)

Now that the change to pass all the signing params
from the managed task is in production, we no longer
need the signing configmaps in internal-services.
Going forward, we only need them in the managed namespace,
set up in the konflux-release-data repo.

Let's start with the stage deployment.

Signed-off-by: Martin Malina <mmalina@redhat.com>

Author: mmalina

components/internal-services/internal-staging/kustomization.yaml

@@ -24,6 +24,3 @@ resources:
 
   # External Secrets
   - es/
-
-  # Signing configurations
-  - signing/