chore(chart): Update appVersion in helm chart (#19653)

This patch updates the helm chart appVersion to the current release and
removes the additional definition in the image tag field, to reduce
duplication.

Since the image will automatically default to the Charts' app version
anyway and this is the more common place to specifiy application
versions for helm charts, this patch switches the prefering this field.

The reason why to use the tag field for the chart itself, seems to be
gone. Since renovatebot is no longer used.