Remove vmdb_database attributes from VmdbDatabaseConnection

[carbonin]

You can't assign to a virtual column and all the other methods caused errors.

[Fryguy]

Can you verify that UI does not blow up with this change?

[carbonin]

Well the UI blows up on the connections page, but it blows up in the same way on master ...

[----] F, [2019-02-11T10:16:52.236114 #14890:2b28dbfe56a8] FATAL -- : Error caught: [ArgumentError] The method .order() must contain arguments.
/home/ncarboni/.gem/ruby/2.4.3/gems/activerecord-5.0.7.1/lib/active_record/relation/query_methods.rb:1214:in `check_if_method_has_arguments!'
/home/ncarboni/.gem/ruby/2.4.3/gems/activerecord-5.0.7.1/lib/active_record/relation/query_methods.rb:338:in `order'
/home/ncarboni/.gem/ruby/2.4.3/bundler/gems/manageiq-ui-classic-2e054446e056/app/controllers/ops_controller/db.rb:29:in `db_list'
/home/ncarboni/.gem/ruby/2.4.3/bundler/gems/manageiq-ui-classic-2e054446e056/app/controllers/ops_controller/db.rb:111:in `db_get_info'
/home/ncarboni/.gem/ruby/2.4.3/bundler/gems/manageiq-ui-classic-2e054446e056/app/controllers/ops_controller.rb:205:in `change_tab'
/home/ncarboni/.gem/ruby/2.4.3/gems/actionpack-5.0.7.1/lib/action_controller/metal/basic_implicit_render.rb:4:in `send_action'
/home/ncarboni/.gem/ruby/2.4.3/gems/actionpack-5.0.7.1/lib/abstract_controller/base.rb:188:in `process_action'

[carbonin]

Opened ManageIQ/manageiq-ui-classic#5235 to fix