Customizing generated deployment labels to fix Jenkins X deployments

[carlossg]

With the helm deployment using templates instead of tiller we are hitting this issue
jenkins-x/jx#3920

because jx will delete all the deployments whose labels do not match jenkins.io/chart-release=jx,jenkins.io/version!=CURRENT_VERSION to cleanup, which includes the generated primary deployment

There are several options to avoid it

1. flagger does not copy the labels from the canary to the primary deployment, because this is making the generated deployment look like it is part of the helm chart. Annotations are not being copied for instance. At least the chart label should probably not be there.
2. flagger canary object adds a spec.deployment.labels section where I can override jenkins.io/chart-release="" or add a jx-do-not-delete type of label
3. jx fixes it maybe not deleting something with ownerReferences or not having an annotation

I'm inclined for 1+2, do not add any label, unless explicitly set in the canary object under spec.deployment.labels

WDYT?

[stefanprodan]

@carlossg Flagger 0.13.2 image and chart are up, please let me know if it solves the issue.