[elasticsearch] Add option to provide custom start/stop hooks

[tetianakravchenko]

• Chart version not bumped (the versions are all bumped and released at the same time)
• README.md updated with any new values or changes
• Updated template tests in ${CHART}/tests/*.py
• Updated integration tests in ${CHART}/examples/*/test/goss.yaml

PR should fix issue: #190

[elasticmachine]

Since this is a community submitted pull request, a Jenkins build has not been kicked off automatically. Can an Elastic organization member please verify the contents of this patch and then kick off a build manually?

[Crazybus]

LGTM! This looks perfect ⭐️

[Crazybus]

jenkins test this please

[tetianakravchenko]

@Crazybus there is some issue on k8s 1.13, not related to the PR :

11:10:30 Error: Nothing to do
11:10:31 The command '/bin/sh -c yum -y install     https://packages.cloud.google.com/yum/pool/654962a43cb6bc6b47bc312424410b7c203e1beb73386d868d9e614839c82609-google-cloud-sdk-215.0.0-1.el7.noarch.rpm &&     gcloud config set core/disable_usage_reporting true &&     gcloud config set component_manager/disable_update_check true &&     gcloud version' returned a non-zero code: 1
11:10:46 Unable to find image 'helm-charts:latest' locally
11:10:46 docker: Error response from daemon: pull access denied for helm-charts, repository does not exist or may require 'docker login'.```

[Crazybus]

None of your changes should be affecting the integration tests. The template testing passed though so good enough https://devops-ci.elastic.co/job/elastic+helm-charts+pull-request+template-testing/73/. I'll look into the flakiness of the other tests but that's unrelated to your changes.

Thank you again for adding this in!

[tetianakravchenko]

@Crazybus any updates on when those changes will be released?