[12.x] Allow globally disabling Factory parent relationships

[cosmastech]

A continuation of #53450. This feature was added by @browner12 and it's been incredibly helpful for our team in speeding up tests.

That said, it requires us to write ->withoutParents() on each factory make, which has led to bugs. Namely, we don't add the trait to refresh the database and then data gets left over between tests, which breaks expectations in other tests... but we don't discover it for a month 😆 😭 and then it's debug city.

It would be great if in the test's setup, we can just indicate no factory should create a parent relationship.

public function test_has_one_editor_permission_returns_true(): void
{
+    UserPermissionFactory::$defaultExpandRelationships = false;
+
    $collection = new UserPermissionCollection([
        UserPermission::factory()
-            ->withoutParents()
            ->make([
                'type' => 'viewer',
                'company_id' => 2,
                'product_id' => 789,
            ]),
        UserPermission::factory()
-            ->withoutParents()
            ->make([
                'type' => 'editor',
                'company_id' => 2,
                'product_id' => 432,
            ]),
    ]);

    $result = $collection->hasEditorForCompany(2);

    $this->assertTrue($result);
}

Even better, I would just add this to the class's setUp() method.

[NickSdot]

Would a descriptive method be more Laravel-y?

UserPermissionFactory::disableExpandedRelationships()