WORKAROUND: Adds flag to disable leader election sidecar in web frontend deployment

The issue arises that the used leader election sidecar image (originating from here github.com/openshift/leader-elector) is not built with OCI v2 manifest or not available any more. Unfortunately, this prevents deployments from starting as the required image cannot be successfully pulled.

As a quick WORKAROUND, this MR introduces the option to disable the sidecar, as a single instance deployment or a deployment with disabled scan-loop should not be effected. A deployment with these features enabled and more than one instance will certainly fail.