only set the loadBalancerClass property when the user sets it to a non-empty value

[rgl]

Description

only set the loadBalancerClass property when the user sets it to a non-empty value.

this allows us to easily use the cluster default load balancer class.

Why is this needed

this is required to use metallb instead of kube-vip.

here's an usage example:

helm upgrade --install \
  stack \
  . \
  --create-namespace \
  --namespace tink-system \
  --wait \
  --values <(cat <<EOF
stack:
  ...
  lbClass: ""
  kubevip:
    enabled: false
boots:
  service:
    class: ""
  ...
EOF
)

How Has This Been Tested?

It was tested in a k3s cluster using metallb.

How are existing users impacted? What migration steps/scripts do we need?

It does not impact existing users as there are no breaking changes.

Checklist:

I have:

• updated the documentation and/or roadmap (if required)
• added unit or e2e tests
• provided instructions on how to upgrade

[chrisdoherty4]

Thanks for the contribution.