Add resource limits to init container otherwise it won't start in namespaces with quotas

Without adding resource limits to every container, a pod won't start in namespaces with resource quotas.

Warning  FailedCreate  1m                replicaset-controller  Error creating: pods "gitlab-runner-gitlab-runner-5d6bff5fdc-ph757" is forbidden: failed quota: mem-cpu-demo: must specify limits.cpu,limits.memory,requests.cpu,requests.memory

I think running gitlab-runner in namespace without quotas should be avoided, as I can otherwise use all the resources by launching endless services, so this should be in there.