Remove connection close from QueueBase::shutdown()

Working on it.

Hi @cmlara,
Done the required changes, pls check.

NW for the PHPstan Baseline ignore removal and an IS update to capture the changes to scope.

updated the baseline and IS.

updated the baseline and IS.

I was more looking for the IS to reflect the change that now the queue channel would be permitted to be re-oppened without having to construct a new queue instance as this significantly changed the scope of the issue from not closing the connection (yet closing the channel), to changing the handling of channel shutdowns and recovery.

On a positive note it allowed queue channels to rebuild themselves if they need to, however on a negative it means there is no way to assure the queue instance is not used to inject more messages. Could this be a concern? Why would we call Shutdown if we just wanted to allow a re-connect?

I'll note the sample uses the Drupal Queue service, though really that is somewhat a bad example (we likely need a separate issue to de-scope this from public) as it only constructs a single instance and has no logic to create a new one, 3rd party API may not have this requirement (symfony non-shared service) so the ability to call createItem() again on the same queue can be considered a non-issue.