feat: add priorityClassName field to a Helm chart

[v-shechenkov]

Feature Description

In Kubernetes, priorityClassName is a field in a Pod's specification that assigns a specific scheduling importance to that Pod. It links the Pod to a PriorityClass object, which defines a numeric value used by the scheduler.

Suggested Solution (optional)

Adding priorityClassName field to a Helm chart which will allow define Pod deployment priority.

Already existing or connected issues / PRs (optional)

#683

[yorugac]

Thanks @v-shechenkov, for the issue and the details! We have priority classes in the TestRun but indeed, not in Helm chart 🤔
I'll add the PR review this week.