Remove unused enabled option, add none option

[LeRaymy]

In the default values.yaml, there is an option enabled for both cluster and standby. But there is any trace of the use of this variable in the templates of the Chart. I suggest to just delete the option.

Furthemore, I suggest to precise that you can chose to deploy just the operator, by adding a value none (or any string different than all|cluster|standby|manager) for the type option.

[DoubleJ213]

Good suggestion to delete useless configuration.
and I 'll enable to add the type none for only installing the operator.