user-status: Delete status field from UserStatus model.

We are no longer writing to or reading the UserStatus.status field,
so we delete that from the model.

Fifth step in making user status `away` a deprecated way to access
`presence_enabled` for clients supporting older servers.

Part of transitioning from 'unavailable' user status feature to
'invisible mode' user presence feature.

zerver/migrations/0414_remove_userstatus_status.py

@@ -0,0 +1,17 @@
+# Generated by Django 4.0.7 on 2022-09-22 12:12
+
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("zerver", "0413_set_presence_enabled_false_for_user_status_away"),
+    ]
+
+    operations = [
+        migrations.RemoveField(
+            model_name="userstatus",
+            name="status",
+        ),
+    ]

zerver/models.py

@@ -4155,10 +4155,7 @@ class UserStatus(AbstractEmoji):
     # default value.
     emoji_name: str = models.TextField(default="")
     emoji_code: str = models.TextField(default="")
-    NORMAL = 0
-    AWAY = 1
 
-    status: int = models.PositiveSmallIntegerField(default=NORMAL)
     status_text: str = models.CharField(max_length=255, default="")