[QE] Allow to change the Eventing upgrate tests SUT (system under test)

[cardil]

Problem
Eventing upgrade tests use static SUT (system under test) - a default broker with trigger.

eventing/test/upgrade/prober/configuration.go

Lines 131 to 133 in 4a3216c

	p.deployBroker()
	p.deployConfigMap()
	p.deployTriggers()

In different cases it's actually required to replace that with different configuration of eventing bits we'd to test. One of such example would be knative-extensions/eventing-kafka#67 - instead of deploying broker+trigger, lets deploy KafkaSource, KafkaTopic, KafkaUser, and feed events to KafkaChannel, and create Subscription that would route events to receiver. Many such configurations can be thought of.

Persona:
Developer

Exit Criteria
I can easily replace

eventing/test/upgrade/prober/configuration.go

Lines 131 to 133 in 4a3216c

	p.deployBroker()
	p.deployConfigMap()
	p.deployTriggers()

with KafkaSource that pushes events to receiver. Or any other source we'd to test upgrades for.

Time Estimate (optional):
2d

[cardil]

/area test-and-release
/assign

[vaikas]

This is precisely what we're trying to address with reconciler-test framework. Our conformance tests do precisely these, so it should be possible to take advantage of this. You can see how we do these for example for rabbitmq to run conformance against rabbitmq:
https://github.com/knative-sandbox/eventing-rabbitmq/tree/main/test/conformance/testdata/with-operator

[vaikas]

@cardil ☝️

[cardil]

@vaikas I'm not sure what you are suggesting. I think I can't use here the reconciler-test framework, as upgrade tests are rather specific. Also, eventing test prober is eventing specific, as it focuses on continual propagation of events. Sorry, but I don't get you, on this...

[vaikas]

I was merely talking about the set up phase, where we can provide the yaml files that set up the tests. So, I meant using it if it works for you, if not, you could probably use some of the installation logic that allows overrides, etc. And if I'm just not getting what your problem is, sorry :)