Merging conditions on the same column no longer maintain both conditions,
and will be consistently replaced by the latter condition.

    ```ruby
    # Rails 6.1 (IN clause is replaced by merger side equality condition)
    Author.where(id: [david.id, mary.id]).merge(Author.where(id: bob)) # => [bob]
    # Rails 6.1 (both conflict conditions exists, deprecated)
    Author.where(id: david.id..mary.id).merge(Author.where(id: bob)) # => []
    # Rails 6.1 with rewhere to migrate to Rails 7.0's behavior
    Author.where(id: david.id..mary.id).merge(Author.where(id: bob), rewhere: true) # => [bob]
    # Rails 7.0 (same behavior with IN clause, mergee side condition is consistently replaced)
    Author.where(id: [david.id, mary.id]).merge(Author.where(id: bob)) # => [bob]
    Author.where(id: david.id..mary.id).merge(Author.where(id: bob)) # => [bob]
    ```