Add validation to config.waitForPodsReady

[PBundyra]

What would you like to be added:
Add validation for WaitForPodsReady that asserts timeout, blockAdmission and requeuingStrategy are defined only if enable is set to True

Why is this needed:

Completion requirements:

This enhancement requires the following artifacts:

• Design doc
• API change
• Docs update

The artifacts should be linked in subsequent comments.

[mimowo]

Hm, not sure about that. What about the use case that an admin has the feature configured and just wants to disable it temporarily and reenable quickly with the same config.

[tenzen-y]

We already checked the waitForPodsReady only when the waitForPodsReady is enabled here:

kueue/pkg/config/validation.go

Lines 118 to 120 in d85a79b

	if !WaitForPodsReadyIsEnabled(c) {
	return allErrs
	}

So, I was not sure this validation motivation.

[PBundyra]

Do we give any feedback to a user in case they configured the rest of the fields, but forgot to switch the enable field?

[mimowo]

I don't think we do, maybe we could leave some useful log or use a warning.

[tenzen-y]

maybe we could leave some useful log or use a warning.

+1