✨ Reduce memory usage of default webhooks

[sbueringer]

Before this PR we were always going through the JSON patch calculation which is pretty expensive.
This PR optimizes this by short-circuting if the objects are equal.

goos: darwin
goarch: arm64
pkg: sigs.k8s.io/controller-runtime/pkg/webhook/admission/bench
cpu: Apple M2 Pro
                          │   old.txt   │              new.txt               │
                          │   sec/op    │   sec/op     vs base               │
Defaulter/noop-12           95.52µ ± 7%   43.50µ ± 2%  -54.46% (p=0.002 n=6)
Defaulter/with_changes-12   89.98µ ± 2%   96.58µ ± 6%   +7.33% (p=0.002 n=6)
geomean                     92.71µ        64.82µ       -30.09%

                          │   old.txt    │               new.txt               │
                          │     B/op     │     B/op      vs base               │
Defaulter/noop-12           52.66Ki ± 0%   22.19Ki ± 0%  -57.86% (p=0.002 n=6)
Defaulter/with_changes-12   52.26Ki ± 0%   55.00Ki ± 0%   +5.25% (p=0.002 n=6)
geomean                     52.46Ki        34.94Ki       -33.40%

                          │  old.txt   │              new.txt              │
                          │ allocs/op  │ allocs/op   vs base               │
Defaulter/noop-12           950.0 ± 0%   217.0 ± 0%  -77.16% (p=0.002 n=6)
Defaulter/with_changes-12   950.0 ± 0%   982.0 ± 0%   +3.37% (p=0.002 n=6)
geomean                     950.0        461.6       -51.41%

[sbueringer]

/cherry-pick release-0.23

[k8s-infra-cherrypick-robot]

@sbueringer: once the present PR merges, I will cherry-pick it on top of release-0.23 in a new PR and assign it to you.

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In response to this:

/cherry-pick release-0.23

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[sbueringer]

/assign @alvaroaleman

[alvaroaleman]

thanks!

[k8s-ci-robot]

LGTM label has been added.

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Git tree hash: 4a51e2c233e415ddfa8c08147eaa7ba7c03b7696

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: alvaroaleman, sbueringer

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[k8s-infra-cherrypick-robot]

@sbueringer: new pull request created: #3467

Details

In response to this:

/cherry-pick release-0.23

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository.