fix: make NotConditions obey De Morgan's laws

[molon]

• Do only one thing
• Non breaking API changes
• Tested

What did this pull request do?

Resolve this issue: #7294

This should be a breaking change, but I think the previous logic is a bug.
Or is it because I don't understand the role of this condition?

User Case Description

[jinzhu]

This change does make sense, but since it is a long-standing behavior, we’d prefer to keep things as they are to avoid breaking existing user systems. Thank you for your PR!

[ezk84]

@jinzhu this was a bug introduced in gorm in 1.25.6 (released Jan 12, 2024).

Testing against 1.25.5 (released Oct 10, 2023) returns the correct condition and expected rows in the included tests (see go-gorm/playground#767).

This doesn't seem like designed behaviour, and it's only been one year and a half that it's been in this faulty state.

I've had to stay at 1.25.6 in my system because I rely on the previous correct logic for negating expressions. I just don't see how the comment about not breaking existing systems makes any sense.