AMI: Install helm command for repo:voltha-helm-charts use

Install the helm command, new/clean AMI used to spawn a jenkins node.

Manual install, helm is not available as a debian/ubuntu package.

Helm version used during the v2.12 release was v3.5.2

Latest version is 3.15.3

% helm version
version.BuildInfo{Version:"v3.15.3", GitCommit:"3bb50bbbdd9c946ba9989fbe4fb4104766302a64", GitTreeState:"clean", GoVersion:"go1.22.5"}

Problems:

• % make lint-chart – see warnings pasted into comments.  Multiple versions strings may confuse lint checking.

• ** WARNING: Unable to identify chart version, multiple strings detected.
  **        : Consider updating the lint tool to be aware of Chart.yaml
  **        : record syntax so versions can be extracted for comparison.