Suppress redundant configuration logging for rubocop-rails

`rubocop-rails/config/default.yml` is being output twice:

```console
$ bundle exec rubocop -d lib/rubocop/rails.rb
For /Users/koic/src/github.com/rubocop/rubocop-rails: configuration from /Users/koic/src/github.com/rubocop/rubocop-rails/.rubocop.yml
configuration from /Users/koic/src/github.com/rubocop/rubocop-rails/config/default.yml
configuration from /Users/koic/.rbenv/versions/3.4.1/lib/ruby/gems/3.4.0/bundler/gems/rubocop-87216abe904e/config/internal_affairs.yml
configuration from /Users/koic/.rbenv/versions/3.4.1/lib/ruby/gems/3.4.0/bundler/gems/rubocop-87216abe904e/config/internal_affairs.yml
Default configuration from /Users/koic/.rbenv/versions/3.4.1/lib/ruby/gems/3.4.0/bundler/gems/rubocop-87216abe904e/config/default.yml
configuration from /Users/koic/.rbenv/versions/3.4.1/lib/ruby/gems/3.4.0/gems/rubocop-performance-1.23.1/config/default.yml
configuration from /Users/koic/.rbenv/versions/3.4.1/lib/ruby/gems/3.4.0/gems/rubocop-performance-1.23.1/config/default.yml
configuration from /Users/koic/src/github.com/rubocop/rubocop-rails/config/default.yml
configuration from /Users/koic/src/github.com/rubocop/rubocop-rails/config/default.yml
```

Since it is already logged by `ConfigLoader.load_yaml_configuration`:
https://github.com/rubocop/rubocop/blob/v1.71.2/lib/rubocop/config_loader.rb#L71-L82

The unnecessary code on the caller side will be removed.

Author: koic

lib/rubocop/rails/inject.rb

@@ -9,9 +9,8 @@ def self.defaults!
         path = CONFIG_DEFAULT.to_s
         hash = ConfigLoader.load_yaml_configuration(path)
         config = Config.new(hash, path).tap(&:make_excludes_absolute)
-        puts "configuration from #{path}" if ConfigLoader.debug?
-        config = ConfigLoader.merge_with_default(config, path, unset_nil: false)
-        ConfigLoader.instance_variable_set(:@default_configuration, config)
+        new_config = ConfigLoader.merge_with_default(config, path, unset_nil: false)
+        ConfigLoader.instance_variable_set(:@default_configuration, new_config)
       end
     end
   end