Default pv controller and scheduler to immediate mode if volume binding mode is nil

[msau42]

What type of PR is this?
@kubernetes/sig-storage-bugs

What this PR does / why we need it:
Allow volume binding mode to be nil even if the feature is enabled to handle HA master component skew. The behavior defaults to immediate mode.

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

Fixes issue where an apiserver on 1.9 and controller-manager on 1.10 can cause volume provisioning and binding to fail.

[msau42]

/priority critical-urgent

[msau42]

/test pull-kubernetes-integration

[msau42]

/assign @MaciekPytel

[msau42]

I also need to update the scheduler
/hold

[msau42]

/hold cancel

[msau42]

/assign @jsafrane @wojtek-t

[jsafrane]

/lgtm

[jsafrane]

/approve

[wojtek-t]

/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: jsafrane, msau42, wojtek-t

The full list of commands accepted by this bot can be found here.

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Needs approval from an approver in each of these files:

• pkg/controller/volume/persistentvolume/OWNERS [jsafrane,wojtek-t]
• pkg/scheduler/OWNERS [wojtek-t]

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[MaciekPytel]

Is that behavior already implemented in newer versions? Just want to make sure there won't be a regression when upgrading from 1.10 to 1.11+.

Also the default is to add a release note, unless it's something like tests or doc change. Even if it's a minor fix for a specific scenario having release note makes it much easier to spot which versions have the fix and which don't.

[msau42]

This is only an issue when upgrading between 1.9->1.10, when the feature went from alpha to beta. You can have apiservers that are still on 1.9 with the feature off, and controller manager on 1.10 with the feature on.

[msau42]

Updated the release note