[1.8.x] Revert "Fixed #24075 -- Prevented running post_migrate signals when unapplying initial migrations of contenttypes and auth"

This reverts commit 737d24923a.

Backport of 2832a9b028 from master

django/db/migrations/loader.py

@@ -5,11 +5,10 @@ import os
 import sys
 
 from django.apps import apps
-from django.db import connection
-from django.db.migrations.recorder import MigrationRecorder
-from django.db.migrations.graph import MigrationGraph, NodeNotFoundError
-from django.utils import six
 from django.conf import settings
+from django.db.migrations.graph import MigrationGraph, NodeNotFoundError
+from django.db.migrations.recorder import MigrationRecorder
+from django.utils import six
 
 
 MIGRATIONS_MODULE_NAME = 'migrations'
@@ -340,14 +339,3 @@ class AmbiguityError(Exception):
     Raised when more than one migration matches a name prefix
     """
     pass
-
-
-def is_latest_migration_applied(app_label):
-    # TODO: Remove when migration plan / state is passed (#24100).
-    loader = MigrationLoader(connection)
-    loader.load_disk()
-    leaf_nodes = loader.graph.leaf_nodes(app=app_label)
-    return (
-        leaf_nodes and leaf_nodes[0] in loader.applied_migrations or
-        app_label in loader.unmigrated_apps
-    )