cmd/storagenode: fix permission to /etc/supervisor in base image

This change fixes the `sed: can't create temp file '/etc/supervisor/supervisord.confXXXXXX': Permission denied` issue when editing the supervisord.conf file during runtime as a non-root user.

While editing the config file, Sed creates a temporary file, saves the result and then finally mv the original file with the temporary one. So we need to set the permission for the /etc/supervisor where the temporary file is created.

Change-Id: Ic9c147a9cf0a6ef94adf702e33054edce1828806

cmd/storagenode/Dockerfile.base

@@ -4,4 +4,5 @@ FROM ${DOCKER_ARCH:-amd64}/alpine:3.15
 RUN apk --no-cache -U add ca-certificates supervisor
 RUN mkdir -p /var/log/supervisor /app
 COPY cmd/storagenode/docker-base/ /
-RUN chmod a+rw /etc/supervisor/supervisord.conf /app
+# set permissions to allow non-root access
+RUN chmod -R a+rw /etc/supervisor /var/log/supervisor /app