Fix retryAfter experimental e2e test

[creydr]

After knative-extensions/reconciler-test#535 and thus distinguishing between received/rejected events, the ReplyAfter e2e test needs to be adjusted.
Currently it fails due to

 - Match errors -
0 - event kind don't match. Expected: 'Sent', Actual: 'Rejected'
1 - event kind don't match. Expected: 'Sent', Actual: 'Rejected'
2 - event kind don't match. Expected: 'Sent', Actual: 'Rejected'

and later

- Match errors -
0 - response received at 2023-08-03 14:33:17.338149413 +0000 UTC, it should have waited until 2023-08-03 14:33:41.369616997 +0000 UTC

as it is not differentiated between received and rejected events.

This PR addresses it and adjust the event matchers.

[knative-prow]

Skipping CI for Draft Pull Request.
If you want CI signal for your change, please convert it to an actual PR.
You can still manually trigger a test run with /test all

[creydr]

/test all

[codecov]

Codecov Report

Patch and project coverage have no change.

Comparison is base (8a90e40) 77.92% compared to head (a9f726a) 77.92%.
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #7148   +/-   ##
=======================================
  Coverage   77.92%   77.92%           
=======================================
  Files         248      248           
  Lines       13257    13257           
=======================================
  Hits        10330    10330           
  Misses       2400     2400           
  Partials      527      527           

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[creydr]

https://github.com/knative/eventing/actions/runs/5760703122/job/15617156355?pr=7148

🎉

/assign @matzew @pierDipi

[matzew]

/lgtm
/approve

[knative-prow]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: creydr, matzew

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