fix: filtering by non-poly relationships with not_equals operator (#7573)

## Description

Fixes #5212

Fixes #6278 

- [x] I have read and understand the
[CONTRIBUTING.md](https://github.com/payloadcms/payload/blob/main/CONTRIBUTING.md)
document in this repository.

## Type of change

- [x] Bug fix (non-breaking change which fixes an issue)

## Checklist:

- [x] I have added tests that prove my fix is effective or that my
feature works
- [x] Existing test suite passes locally with my changes

test/fields/collections/Relationship/index.ts

@@ -31,6 +31,18 @@ const RelationshipFields: CollectionConfig = {
         },
       },
     },
+    {
+      name: 'relationNoHasManyNonPolymorphic',
+      relationTo: 'text-fields',
+      type: 'relationship',
+      hasMany: false,
+    },
+    {
+      name: 'relationHasManyNonPolymorphic',
+      relationTo: 'text-fields',
+      type: 'relationship',
+      hasMany: true,
+    },
     {
       name: 'relationToSelf',
       relationTo: relationshipFieldsSlug,