[1.5.x] Fixed #23431 -- Allowed inline and hidden references to admin fields.

This fixes a regression introduced by the 53ff096982 security fix.

Thanks to @a1tus for the report and Tim for the review.

refs #23329.

Backport of 342ccbd from master

tests/regressiontests/admin_views/models.py

@@ -696,3 +696,15 @@ class ChildOfReferer(ParentWithFK):
 class M2MReference(models.Model):
     ref = models.ManyToManyField('self')
 
+# Models for #23431
+class ReferencedByInline(models.Model):
+    pass
+
+
+class InlineReference(models.Model):
+    fk = models.ForeignKey(ReferencedByInline, related_name='hidden+')
+
+
+class InlineReferer(models.Model):
+    refs = models.ManyToManyField(InlineReference)
+