Story

As a user of the RHDH Helm Chart, I want to have the dynamic plugin cache disabled by default so that it doesn't prevent me from performing upgrades and so that I can have more control.

Background

See RHIDP-5516 for more context.

Dependencies and Blockers

QE impacted work

Documentation impacted work

Acceptance Criteria

upstream documentation updates (design docs, release notes etc)

Technical enablement / Demo

• It should provide a configurable parameter to help decide whether to create a dynamic plugins root PVC or not, for example by exposing a new "dynamicPlugins.cache.ephemeral" boolean field in the default values.yaml file (default value set to "true")
• It should conditionally create the dynamic plugins PVC based on this parameter: https://github.com/redhat-developer/rhdh-chart/blob/main/charts/backstage/templates/pvcs.yaml#L1-L6 
• It should conditionally mount the dynamic plugins extra-volume either as an ephemeral volume claim or as a persistent volume claim, based on the configurable value above: https://github.com/redhat-developer/rhdh-chart/blob/main/charts/backstage/values.yaml#L144-L146 
• In either case, the claim spec should come from "dynamicPlugins.cache.volumeClaimSpec" (so that the recently-added ability to configure the storage class is not broken for example)