Add cooldownPeriod in HTTPScaledObject

[veptechno]

Right now cooldownPeriod in ScaledObject is not set, so this field has the default value. But in my project, it is important to set this value for each deployment separately.
I think this field would be useful. If you approve, I can try to add it.

[tomkerkhove]

@arschles Can we change it so that the default SO "control" flags are available through the HTTPScaledObject?

[veptechno]

@tomkerkhove From what I can see, we need to add only cooldownPeriod. It looks like poolingInterval value 1s should remain default and there is no need for it to be configurable, and there are no other control flags as I see.

[arschles]

@veptechno how about we start with cooldownPeriod to see how it looks and avoid blowup of scope. If we do want to add more flags, we can do so in follow-ups.

[tpiperatgod]

This is similar to the need in issue #332, so maybe it can be integrated into the discussion?

[arschles]

@tpiperatgod do you see a reason to ever have the operator not set spec.advanced.restoreToOriginalReplicaCount to true? If we can always set it to true, we don't have to change anything with the HTTPScaledObject, which would make that work simpler. If not, I agree that we could combine the two pieces of work. I just think we should avoid building something that allows users to arbitrarily set any ScaledObject field from within the HTTPScaledObject, at least for now.

[tpiperatgod]

Get it. Thx!