Follow-up of 5c71000, #29834, and #30271.
Currently, preloading and eager loading are not to be affected by
scoping, with the exception of `unscoped`.
But non eager loaded association access is still affected by scoping.
Although this is a breaking change, the association loading will work
consistently whether preloaded / eager loaded or not.
Before:
```ruby
Post.where("1=0").scoping do
Comment.find(1).post # => nil
Comment.preload(:post).find(1).post # => #<Post id: 1, ...>
Comment.eager_load(:post).find(1).post # => #<Post id: 1, ...>
end
```
After:
```ruby
Post.where("1=0").scoping do
Comment.find(1).post # => #<Post id: 1, ...>
Comment.preload(:post).find(1).post # => #<Post id: 1, ...>
Comment.eager_load(:post).find(1).post # => #<Post id: 1, ...>
end
```
Fixes#34638.
Fixes#35398.
17f2f3054c