Speed up a few tests (backport #13002)

[mergify]

Multiple test cases were recently slowed down by up to 30 seconds. This commit reverts these changes.

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This is an automatic backport of pull request #13002 done by Mergify.

[mergify]

Cherry-pick of 42ede4a has failed:

On branch mergify/bp/v4.0.x/pr-13002
Your branch is up to date with 'origin/v4.0.x'.

You are currently cherry-picking commit 42ede4a25.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	modified:   deps/rabbitmq_mqtt/test/util.erl

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   deps/rabbit/test/amqp_client_SUITE.erl

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally