prometheus-adapter: remove deprecated argument

The `--logtostderr` argument has been deprecated in v0.10.0 and removed
in v0.11.0.

Signed-off-by: Simon Pasquier <spasquie@redhat.com>

manifests/prometheusAdapter-deployment.yaml

@@ -32,7 +32,6 @@ spec:
       - args:
         - --cert-dir=/var/run/serving-cert
         - --config=/etc/adapter/config.yaml
-        - --logtostderr=true
         - --metrics-relist-interval=1m
         - --prometheus-url=http://prometheus-k8s.monitoring.svc:9090/
         - --secure-port=6443