Improve zookeeper scaleout

[Slach]

Thanks for taking the time to contribute to clickhouse-operator!

Please, read carefully instructions on how to make a Pull Request.

This will help a lot for maintainers to adopt your Pull Request.

Important items to consider before making a Pull Request

Please check items PR complies to:

• [ ] All commits in the PR are squashed. More info
• [ ] The PR is made into dedicated next-release branch, not into master branch¹. More info
• [ ] The PR is signed. More info

--

¹ If you feel your PR does not affect any Go-code or any testable functionality (for example, PR contains docs only or supplementary materials), PR can be made into master branch, but it has to be confirmed by project's maintainer.