Generate new uuid for newly registered iso nodes

When provisioning a new isolated node, generate a new uuid instead of
reusing the SYSTEM_UUID of the controller node.

awx/main/migrations/0101_v370_generate_new_uuids_for_iso_nodes.py

@@ -0,0 +1,24 @@
+# -*- coding: utf-8 -*-
+from uuid import uuid4
+
+from django.db import migrations
+
+from awx.main.models import Instance
+
+
+def _generate_new_uuid_for_iso_nodes(apps, schema_editor):
+    for instance in Instance.objects.all():
+        if instance.is_isolated():
+            instance.uuid = str(uuid4())
+            instance.save()
+    
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('main', '0100_v370_projectupdate_job_tags'),
+    ]
+
+    operations = [
+        migrations.RunPython(_generate_new_uuid_for_iso_nodes)
+    ]