Remove TACACS+ authentication (#15547)

Remove TACACS+ authentication from AWX.

Co-authored-by: Hao Liu <44379968+TheRealHaoLiu@users.noreply.github.com>

awx/conf/migrations/0011_remove_tacacs_plus_auth_conf.py

@@ -0,0 +1,26 @@
+from django.db import migrations
+
+TACACS_PLUS_AUTH_CONF_KEYS = [
+    'TACACSPLUS_HOST',
+    'TACACSPLUS_PORT',
+    'TACACSPLUS_SECRET',
+    'TACACSPLUS_SESSION_TIMEOUT',
+    'TACACSPLUS_AUTH_PROTOCOL',
+    'TACACSPLUS_REM_ADDR',
+]
+
+
+def remove_tacacs_plus_auth_conf(apps, scheme_editor):
+    setting = apps.get_model('conf', 'Setting')
+    setting.objects.filter(key__in=TACACS_PLUS_AUTH_CONF_KEYS).delete()
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('conf', '0010_change_to_JSONField'),
+    ]
+
+    operations = [
+        migrations.RunPython(remove_tacacs_plus_auth_conf),
+    ]