helpers.async_bulk to return explicit tuple.

[bshakur8]

in Python3.11, when stats_only is False, it returns a tuple of (success, errors) instead of only list of errors.
The fix makes sure that it returns a tuple when stats_only is True and list otherwise.

Legacy:

elasticsearch/_async/helpers.py:348
return success, failed if stats_only else errors

will return, <success>, errors in case stats_only is False./

[elasticmachine]

Since this is a community submitted pull request, a Jenkins build has not been kicked off automatically. Can an Elastic organization member please verify the contents of this patch and then kick off a build manually?

[cla-checker-service]

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