Kubernetes `surge_upgrade` field cannot be set to `false`

[pcman312]

tl;dr: The SurgeUpgrade field in KubernetesClusterUpdateRequest should not have omitempty in the struct tags. This is preventing users from turning off surge_upgrade after the K8S cluster has been created.

Reproduction steps:

1. Create K8S cluster in DO. Make sure the surge_upgrade field is set to true
2. Using godo, update the cluster to disable surge_upgrade

Expected result:
surge_upgrade should be turned off

Actual result:
surge_upgrade is still on

It may be worthwhile looking for other non-pointer booleans with omitempty on them as well to check if they have the same issue.

[ChiefMateStarbuck]

hello @pcman312 . thank you for the bug report. I've passed this on to the relative team and will have an answer for you shortly.

[timoreimann]

Closing this PR out: at this point, enabling surge upgrades should come with no disadvantages anymore, neither financially nor functionally. We'll officially deprecate the flag going forward.

[timoreimann]

Actually, reopening to track the deprecation still.