Extend helm chart to improve controller availability

[MM53]

While installing the operator in our setup we did some modifications to the resources to improve the availability of the controller Pods. Since those changes might also help others, it would be great to include them in the Helm chart.

Following changes were applied:

• Add a value to set the priorityClassName of the Deployment and Jobs. This supports proper handling of scheduling and eviction in case of low resources
• Allow to configure topologySpreadConstraints of the controller Pods. This provides a more detailed control of Pod placement than affinity rules.
• Add an optional PodDisruptionBudget to avoid evicting all controller Pods at once in case there are multiple replicas.

Please let me know what you think about these changes.

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