Adopt transform func to save memory

[dddddai]

What type of PR is this? /kind feature

What this PR does / why we need it: https://github.com/karmada-io/karmada/pull/1858#issuecomment-1134114741 Now it just removes metadata.ManagedFields since it's large and we never use it

Which issue(s) this PR fixes: Fixes #1866

Special notes for your reviewer: Looking forward to how much memory this can save

Does this PR introduce a user-facing change?:

NONE

[RainbowMango]

Looking forward to how much memory this can save

Yeah, me too. How to measure it? I've no idea.

[Poor12]

Since it is only related to informer, maybe we can use benchmark to simulate it.

[snowplayfire]

Is there measurement result now?

[RainbowMango]

Is there measurement result now?

@dddddai Is there a way that we can measure the improvement?

[dddddai]

Sorry I'm not very familiar with performance testing

Since it is only related to informer, maybe we can use benchmark to simulate it.

Yeah it would be simple to benchmark the informer cache(with pprof?), but for the whole system, how can we tell how much memory "the informer part" consumes?

[RainbowMango]

/assign

[karmada-bot]

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[dddddai]

Glad to see it works :)