DRY the config and the init containers that are in each elasticsearch node

Currently, there are a lot of redundancies populating the config and initContainers that can be shared under a common key for config and initContainer. Example is in bigbang template folder for elasticsearch/values.yaml for master and data, etc initContainers

Acceptance Criteria

• Create a common config and initContainers that can be used for all nodes of Elasticsearch
• Ensure a graceful merge for the initContainers and Config common key for all nodes when configs are supplied at the per node level
• Backwards compatibility