Use 1-1 helm chart versioning strategy

[jfallows]

Today, our helm chart has the following default image tag and pull policy.

zilla/cloud/helm-chart/src/main/helm/values.yaml

Lines 18 to 21 in c845b9d

	image:
	repository: ghcr.io/aklivity/zilla
	pullPolicy: IfNotPresent
	tag: latest

We prefer to make the chart version and zilla (app) version align 1-1, rather than pulling latest by default.

The pull policy can most likely be removed from values.yaml to pick up the default default behavior, which is IfNotPresent for versioned tags and Always for latest tag.

The tag can be changed to match the zilla release version. Note unless directly supported by the Maven docker plugin, this requires use of Maven filtered resources to inject ${project.version} into values.yaml during the zilla helm-chart build instead of the literal latest tag value.

Suggest including a ZILLA_VERSION environment variable with value coming from ${project.version} that simplifies detection of the current version as well.