Remove middleware/hawkular code

[himdel]

Hawkular support was removed in early 2018, yet:

manageiq/$ ag middleware | wc -l
938
manageiq/$ ag hawkular | wc -l
156

@miq-bot add_label technical debt

Related to:

• Remove hawkular/middleware code manageiq-ui-classic#6268
• Missing migrations for hawkular removal manageiq-schema#423

[djberg96]

I see the following files in core that contain "Hawkular":

• lib/active_metrics/connection_adapters/hawkular_metrics_adapter.rb
• app/models/middleware_performance.rb
• app/models/middleware_server.rb
• app/models/middleware_datasource.rb
• app/models/middleware_messaging.rb
• app/models/container_node.rb # comment only
• spec/factories/middleware_server_group.rb
• spec/factories/middleware_datasource.rb
• spec/factories/middleware_servers.rb
• spec/factories/middleware_messaging.rb
• spec/factories/middleware_domain.rb
• spec/models/ext_management_system_spec.rb