ActiveGate pods support setting PriorityClass

[mjgrzybek]

Description

ActiveGate pods support assigning PriorityClass to them.

How can this be tested?

Play with enabling and disabling PriorityClass for AG:

apiVersion: dynatrace.com/v1beta1
kind: DynaKube
metadata:
  name: dk
  namespace: dynatrace
spec:
  apiUrl: <your_apiurl>
  activeGate:
    capabilities:
    - kubernetes-monitoring
    priorityClassName: high-priority  
---
apiVersion: scheduling.k8s.io/v1
kind: PriorityClass
metadata:
  name: high-priority
value: 1000000
globalDefault: false
description: "high-priority"

Checklist

• Unit tests have been updated/added
• PR is labeled accordingly