Consolidate duplicate intMax helper in KPA and HPA reconcilers

[jahnavigajjala-3]

Current Behavior:
The intMax helper function is implemented independently in both:

pkg/reconciler/autoscaling/kpa/kpa.go
pkg/reconciler/autoscaling/hpa/hpa.go

Both implementations are functionally identical but maintained separately.

Problem:
Duplicate logic means any future change to intMax needs to be applied in two places, increasing maintenance overhead and the risk of the implementations diverging over time.

Proposed Solution:
Move intMax to a shared internal package (e.g. pkg/reconciler/autoscaling/resources) and update both reconcilers to use the shared implementation instead of their local copies.

[linkvt]

Hm these are just 5 lines and could be replaced today with just max(), I don't think a separate package is worth it.

serving/pkg/reconciler/autoscaling/kpa/kpa.go

Lines 354 to 359 in dbce551

	func intMax(a, b int32) int32 {
	if a < b {
	return b
	}
	return a
	}

Will you create the PR?

/kind cleanup

[jahnavigajjala-3]

@linkvt Thanks for the review! I've opened PR #16665. When you have some time, could you please take a look? Thanks!