Controller panics when ingress TLS is configured

When global.ingress.tls evaluates to true, e.g. when ingress TLS is configured and global.ingress.tls.* is set, the self-signed certificates Job is not included in the template (noting that global.ingress.configureCertmanager is always false). This could be a problem with the Chart, but this will cause controller to panic.

In this circumstances gitlabctl.SelfSignedCertsJob returns nil value which will be passed to GitLabReconciler.runJobAndWait and causes nil pointer dereferencing panic.