Association loading isn't to be affected by scoping consistently

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.

1 files changed, 2 insertions, 2 deletions

diff --git a/activerecord/test/cases/scoping/relation_scoping_test.rb b/activerecord/test/cases/scoping/relation_scoping_test.rb
index a95ab0f429..8ab0782bbf 100644
--- a/activerecord/test/cases/scoping/relation_scoping_test.rb
+++ b/activerecord/test/cases/scoping/relation_scoping_test.rb
@@ -411,7 +411,7 @@ class HasManyScopingTest < ActiveRecord::TestCase
 
   def test_nested_scope_finder
     Comment.where("1=0").scoping do
-      assert_equal 0, @welcome.comments.count
+      assert_equal 2, @welcome.comments.count
       assert_equal "a comment...", @welcome.comments.what_are_you
     end
 
@@ -452,7 +452,7 @@ class HasAndBelongsToManyScopingTest < ActiveRecord::TestCase
 
   def test_nested_scope_finder
     Category.where("1=0").scoping do
-      assert_equal 0, @welcome.categories.count
+      assert_equal 2, @welcome.categories.count
       assert_equal "a category...", @welcome.categories.what_are_you
     end