[WIP] Default to miq_messaging for event_handler

[agrare]

Default to miq_messaging/kafka for event_hander dequeue_method

TODO:

• [ ] Fallback to drb if kafka isn't set up
• [ ] Enqueue events with miq_queue if event_handler isn't set up to dequeue with miq_messaging
• [ ] Move messaging_type out of Settings.prototype (will require a data migration)

https://github.com/ManageIQ/manageiq/issues/20027

[miq-bot]

Checked commits https://github.com/agrare/manageiq/compare/4d81b0a08884da89062ff61a83d7a558fbf2c4eb~...0d386d938fa966b6c8163b0dc25bbd640c6bba60 with ruby 2.6.9, rubocop 1.19.1, haml-lint 0.35.0, and yamllint 2 files checked, 0 offenses detected Everything looks fine. :star:

[Fryguy]

Replaced by https://github.com/ManageIQ/manageiq/pull/21997