Add initContainers to templates

[CodePrometheus]

Motivation

Fixes #491,#240

Modifications

• Add initContainers to the templates of each component.
• Add examples/values-init-containers.yaml.

Verifying this change

• Make sure that the change passes the CI checks.

[CodePrometheus]

The CI error does not seem to be related to this change.

+ /home/runner/work/pulsar-helm-chart/pulsar-helm-chart/output/bin/kubectl exec -n pulsar pulsar-ci-toolset-0 -- bin/pulsar-admin tenants create pulsar-ci
null

Reason: java.util.concurrent.CompletionException: org.apache.pulsar.client.admin.internal.http.AsyncHttpConnector$RetryException: Could not complete the operation. Number of retries has been exhausted. Failed reason: pulsar-ci-broker

@lhotari Teacher Lari, could you help with code review, thanks.

[lhotari]

thanks for the contribution @CodePrometheus! Great work

[lhotari]

LGTM