feat(helm): initContainers values as list

[michaelbeaumont]

Why is this PR required? What issue does it fix?:
Fixes #676

What this PR does:
Treats the *.initContainers values as lists instead of maps.

Does this PR require any upgrade changes?:
Any use of initContainers values must be changed to a list.

If the changes in this PR are manually verified, list down the scenarios covered::

Any additional information for your reviewer? :
Mention if this PR is part of any design or a continuation of previous PRs

Checklist:

• Fixes #
• PR Title follows the convention of <type>(<scope>): <subject>
• Has the change log section been updated?
• Commit has unit tests
• Commit has integration tests
• (Optional) Are upgrade changes included in this PR? If not, mention the issue/PR to track:
• (Optional) If documentation changes are required, which issue on https://github.com/openebs/website is used to track them: