Workaround cloud-init hotplug issue

cloud-init added a hook which triggers on every device add/rm
event, which results in holding open devices for a while after
they're created/destroyed.

So let's shove an exclusion rule for that into the GH workflows
until it gets fixed.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: George Melikov <mail@gmelikov.ru>
Reviewed-by: John Kennedy <john.kennedy@delphix.com>
Signed-off-by: Rich Ercolani <rincebrain@gmail.com>
Closes #12644
Closes #12669