[Feature] Leader election settings should be increased and made configurable in chart manifests

[amshuman-kr]

Feature (What you would like to be added):
Leader election settings should be increased and made configurable in chart manifests.

Motivation (Why is this needed?):
The default leader election settings in controller-runtime seem to create too much load on the apiserver. It should be possible to configure them to reduce load on the apiserver without having to make any changes to etcd-druid.

Approach/Hint to the implement solution (optional):
We can introduce command-line flags and chart manifest flags along the lines of gardener/gardener#2667.

Also, it would be desirable to switch to Lease for leader election rather than ConfigMap. But controller-runtime still uses ConfigMap. So, for this, we either have to wait till controller-runtime move to Lease or we override with a custom newResourceLock factory function in the options.

[amshuman-kr]

Closed by #141.

[shreyas-s-rao]

@amshuman-kr But we would still have to introduce the cmd line parameters in druid, along the lines of gardener-attic/gardener-resource-manager#72 and then pass the configs from gardener or use the default values, right?