Fix issues with dependencies when using external Zookeeper

[danielskowronski]

Fixes #60

This chart depends on bitnami/common helper chart for common.storage.class. It is indirectly pulled as dependency to bitnami/zookeeper. However, the latter one is only loaded when this chart is set to install Zookeeper. Therefore, users wanting to use external one (via zookeeper.enabled=false value) are excluding bitnami/common helper, making common.storage.class invalid.

This PR adds explicit import for bitnami/common with associated tarball to conform with build workflow. Moreover, zookeeper repository URL has been updated as per bitnami/charts#10539

Validation commands:

# manually install Zookeeper to have something external working
helm install zk oci://registry-1.docker.io/bitnamicharts/zookeeper

# install this updated chart pointing to external Zookeeper
helm install storm ./ --set zookeeper.enabled=false --set zookeeper.servers='{zk-zookeeper.default.svc}'