Refactor tempo into passthrough pattern

In order to make chart maintenance simple, we should refactor this chart into a passthrough chart that includes the upstream chart as a dependency.

Acceptance Criteria:

• Chart is a wrapper to the upstream tempo chart
• All additional templates remain
• Custom changes to templates added to the HelmRelease a postrender as json patches
• BigBang values.yaml templates updated
• package upgrades without intervention (it should)