Avoid hitting the database at factory definition time

Factory bot rails's railtie tries to find factory definitions during the rails
initialization hooks at rails startup.

Previously, the miq_region.rb factory was running MiqRegion.my_region_number
early to avoid tests that might stub my_region_number later.

This caused a failure in our bin/test_database_connectivity test as we were
now connecting to the database during our initializers.

To fix this, we can lazily evaluate the underlying method,
region_number_from_sequence, called by my_region_number when we create the region.

Here is the backtrace of the failure that was occurring in the test:

```
/home/runner/work/manageiq/manageiq/vendor/bundle/ruby/3.3.0/gems/activerecord-id_regions-0.5.0/lib/active_record/id_regions.rb:128:in `region_number_from_sequence'
/home/runner/work/manageiq/manageiq/vendor/bundle/ruby/3.3.0/gems/activerecord-id_regions-0.5.0/lib/active_record/id_regions.rb:139:in `discover_my_region_number'
/home/runner/work/manageiq/manageiq/vendor/bundle/ruby/3.3.0/gems/activerecord-id_regions-0.5.0/lib/active_record/id_regions.rb:18:in `my_region_number'
/home/runner/work/manageiq/manageiq/spec/factories/miq_region.rb:2:in `block in <main>'
/home/runner/work/manageiq/manageiq/vendor/bundle/ruby/3.3.0/gems/factory_bot-6.5.5/lib/factory_bot/syntax/default.rb:37:in `instance_eval'
/home/runner/work/manageiq/manageiq/vendor/bundle/ruby/3.3.0/gems/factory_bot-6.5.5/lib/factory_bot/syntax/default.rb:37:in `run'
/home/runner/work/manageiq/manageiq/vendor/bundle/ruby/3.3.0/gems/factory_bot-6.5.5/lib/factory_bot/syntax/default.rb:7:in `define'
/home/runner/work/manageiq/manageiq/spec/factories/miq_region.rb:1:in `<main>'
/home/runner/work/manageiq/manageiq/vendor/bundle/ruby/3.3.0/gems/factory_bot-6.5.5/lib/factory_bot/find_definitions.rb:20:in `load'
/home/runner/work/manageiq/manageiq/vendor/bundle/ruby/3.3.0/gems/factory_bot-6.5.5/lib/factory_bot/find_definitions.rb:20:in `block (2 levels) in find_definitions'
/home/runner/work/manageiq/manageiq/vendor/bundle/ruby/3.3.0/gems/factory_bot-6.5.5/lib/factory_bot/find_definitions.rb:19:in `each'
/home/runner/work/manageiq/manageiq/vendor/bundle/ruby/3.3.0/gems/factory_bot-6.5.5/lib/factory_bot/find_definitions.rb:19:in `block in find_definitions'
/home/runner/work/manageiq/manageiq/vendor/bundle/ruby/3.3.0/gems/factory_bot-6.5.5/lib/factory_bot/find_definitions.rb:15:in `each'
/home/runner/work/manageiq/manageiq/vendor/bundle/ruby/3.3.0/gems/factory_bot-6.5.5/lib/factory_bot/find_definitions.rb:15:in `find_definitions'
/home/runner/work/manageiq/manageiq/vendor/bundle/ruby/3.3.0/gems/factory_bot_rails-6.5.1/lib/factory_bot_rails/railtie.rb:42:in `block in <class:Railtie>'
/home/runner/work/manageiq/manageiq/vendor/bundle/ruby/3.3.0/gems/activesupport-7.2.2.2/lib/active_support/lazy_load_hooks.rb:94:in `block in execute_hook'
```

Author: jrafanie

spec/factories/miq_region.rb

@@ -1,7 +1,7 @@
 FactoryBot.define do
-  region_remote = MiqRegion.my_region_number
-
   factory :miq_region do
-    sequence(:region) { |region| region == region_remote ? region + 1 : region }
+    sequence(:region) do |region|
+      region == ApplicationRecord.region_number_from_sequence ? region + 1 : region
+    end
   end
 end