Fixes#36581.
This fixes an issue where validations would return differently when a previously saved invalid association was loaded between calls:
assert_equal true, squeak.valid?
assert_equal true, squeak.mouse.present?
assert_equal true, squeak.valid?
Here the second assert would return
Expected: true
Actual: false
Limiting validations to associations that would be normally saved (using autosave: true) due to changes means that loading invalid associated relations will not change the return value of the parent relations's `valid?` method.
