Add retries for webhook fails at conformance tests

[aliok]

Fixes #3952

Proposed Changes

• Add retries for webhook fails at conformance tests
• Only for conformance test helpers are checked

Release Note

Docs

[aliok]

cc @vaikas @pierDipi

I just added the retries to the places I personally thought applicable in conformance test helpers.
Let me know if you think there is still more work here.

[knative-test-reporter-robot]

The following jobs failed:

Test name	Triggers	Retries
pull-knative-eventing-conformance-tests		0/3

Failed non-flaky tests preventing automatic retry of pull-knative-eventing-conformance-tests:

.Test

[pierDipi]

After retrying we sometimes got an already exists error, can you add a check for that?

eventing/test/lib/creation.go

Lines 81 to 92 in c5fabfd

	var gvr schema.GroupVersionResource
	err := c.RetryWebhookErrors(func(attempts int) (err error) {
	var e error
	gvr, e = duck.CreateGenericChannelObject(c.Dynamic, metaResource)
	if e != nil {
	c.T.Logf("Failed to create %q %q: %v", channelTypeMeta.Kind, name, e)
	}
	return e
	})
	if err != nil && !errors.IsAlreadyExists(err) {
	c.T.Fatalf("Failed to create %q %q: %v", channelTypeMeta.Kind, name, err)
	}

Suggested change

	if err != nil {
	if err != nil && !apierrors.IsAlreadyExists(err) {

The same applies for the others below.

[aliok]

I only added retries for GET operations and I don't think we would get that error in this case.

And, all the other operations already have retries.

Let me know what you think @pierDipi

[pierDipi]

It sounds good, thanks!
/lgtm

[matzew]

thanks, Ali

/lgtm
/approve

[knative-prow-robot]

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