remove system tracking

* Leave the artisanal handcrafted migration from vendored fact scan to
external fact gathering.

awx/main/migrations/0071_v350_remove_system_tracking.py

@@ -0,0 +1,26 @@
+# -*- coding: utf-8 -*-
+# Generated by Django 1.11.16 on 2019-04-10 12:25
+from __future__ import unicode_literals
+
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('main', '0070_v350_gce_instance_id'),
+    ]
+
+    operations = [
+        migrations.AlterIndexTogether(
+            name='fact',
+            index_together=set([]),
+        ),
+        migrations.RemoveField(
+            model_name='fact',
+            name='host',
+        ),
+        migrations.DeleteModel(
+            name='Fact',
+        ),
+    ]