feat: make podDisruptionBudget minAvailable/maxUnavailable configurable

[aramase]

• make minAvailable and maxUnavailable configurable in helm charts
• opened Use maxUnavailable: 1 instead of minAvailable in pod disruption budget #826 to track setting maxUnavailable instead of minAvailable.

fixes #824

[enj]

This LGTM but how exactly do we test that it works?

[aramase]

This LGTM but how exactly do we test that it works?

With this PR, we're only changing the default value to be customizable. We can try to add a drain test (if possible) with #826 to validate this behavior.