stop opinionating webhook namespaceselector field

[akalenyu]

What this PR does / why we need it:
CDI opinionates the namespace selector field
which makes it play badly in case something is mutating this field.
Since we don't care we can just leave empty and allow merging with our desired spec.

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 #3810

Special notes for your reviewer:

Release note:

BugFix: unset namespace selector on webhooks to allow cloud provider mutation

[kubevirt-bot]

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[akalenyu]

/cc @mhenriks

[coveralls]

coverage: 59.527% (+0.03%) from 59.502%
when pulling 54daa5f on akalenyu:webhook-ns-selector
into 91f8cda on kubevirt:main.

[Acedus]

/lgtm

[akalenyu]

/test pull-containerized-data-importer-e2e-istio
#3831 (comment)

[kubevirt-bot]

Pull requests that are marked with lgtm should receive a review
from an approver within 1 week.

After that period the bot marks them with the label needs-approver-review.

/label needs-approver-review

[akalenyu]

/cc @mhenriks

[mhenriks]

@akalenyu have you tested upgrade? I think it should work

[akalenyu]

@akalenyu have you tested upgrade? I think it should work

we have an upgrade lane on PRs in CDI that does this
EDIT: actually, most lanes perform an upgrade from latest->current hash

[mhenriks]

@akalenyu have you tested upgrade? I think it should work

we have an upgrade lane on PRs in CDI that does this EDIT: actually, most lanes perform an upgrade from latest->current hash

but does the upgrade test verify (or you personally) that NamespaceSelector is unset after the upgrade?

[akalenyu]

@akalenyu have you tested upgrade? I think it should work

we have an upgrade lane on PRs in CDI that does this EDIT: actually, most lanes perform an upgrade from latest->current hash

but does the upgrade test verify (or you personally) that NamespaceSelector is unset after the upgrade?

I didn't, I am relying on the CR not being able to reach Available=true if the desired state couldn't be reached

[akalenyu]

@mhenriks so apparently there is in fact a DIFF spam over the default being the empty selector AND this PR won't make a different selector go through unchanged by us
/hold