Remove tag+digest on shell-image 🍶

Some runtime (cri-o) do not support tag+digest notation on image
reference. Removing this on shell-image to fix the `notags` release
yamls.

Signed-off-by: Vincent Demeester <vdemeest@redhat.com>
(cherry picked from commit a6830f7)

config/controller.yaml

@@ -77,8 +77,8 @@ spec:
           # This is google/cloud-sdk:293.0.0-slim
           "-gsutil-image", "google/cloud-sdk@sha256:37654ada9b7afbc32828b537030e85de672a9dd468ac5c92a36da1e203a98def",
           # The shell image must be root in order to create directories and copy files to PVCs.
-          # As of May 19, 2020
-          "-shell-image", "gcr.io/distroless/base:debug@sha256:f79e093f9ba639c957ee857b1ad57ae5046c328998bf8f72b30081db4d8edbe4",
+          # gcr.io/distroless/base:debug as of May 19, 2020
+          "-shell-image", "gcr.io/distroless/base@sha256:f79e093f9ba639c957ee857b1ad57ae5046c328998bf8f72b30081db4d8edbe4",
         ]
         volumeMounts:
         - name: config-logging