Add support for priority classes

[SansGuidon]

Is your feature request related to a problem? Please describe.
Context : in our production cluster, some workloads such as neo4j database are more critical than others so we need that reflected in terms of priority classes for pods. We need to ensure those workloads have very high priority so our cluster is functional. Unfortunately the Neo4J helm charts do not expose priorityClassName attribute, which is not blocking but forces us to find workarounds.

Describe the solution you'd like
Something like neo4j-contrib/neo4j-helm#250 and #1
Official documentation: https://kubernetes.io/docs/concepts/scheduling-eviction/pod-priority-preemption/

Describe alternatives you've considered
Using kustomize to post-render Neo4j helm chart.

Additional context
Related issue : neo4j-contrib/neo4j-helm#227
Related PRs :

• Adds support for priority classes (4.3) #2
• Adds support for priority classes (4.4) #1
• Fix #227 support for priority classes neo4j-contrib/neo4j-helm#250
  Official documentation: https://kubernetes.io/docs/concepts/scheduling-eviction/pod-priority-preemption/

[harshitsinghvi22]

@MorganGeek
Support for priority classes released in 4.4.9
https://github.com/neo4j/helm-charts/releases/tag/4.4.9