6.8.3 release backport

[ezimuel]

This is a meta ticket to collect all the PRs that we would like to backport in 6.8.3:

• [ ] Fix #1074 allowing multiple function parameters in fromConfig (see https://github.com/elastic/elasticsearch-php/pull/1076)
• [ ] 401 - Unauthorized Code Exception Handling (see https://github.com/elastic/elasticsearch-php/issues/1097)
• [ ] Remove unnecessary InvalidArgumentExceptions (see https://github.com/elastic/elasticsearch-php/commit/2215c18fa131e33f6e4af5167981b1280e6ebaa0)
• [ ] Output json_last_error_msg instead of json_last_error (see https://github.com/elastic/elasticsearch-php/pull/1045)