notify user task patch + small update to user notification rules publ…

…ic API docs (#4628)

# What this PR does

Patches a small bug noticed (locally) by @Ferril 🙏 + updates our user
notification rules public API docs to include `notify_by_msteams` as a
valid `type` value (cloud only)

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## Checklist

- [ ] Unit, integration, and e2e (if applicable) tests updated
- [ ] Documentation added (or `pr:no public docs` PR label added if not
required)
- [x] Added the relevant release notes label (see labels prefixed w/
`release:`). These labels dictate how your PR will
    show up in the autogenerated release notes.

docs/sources/oncall-api-reference/personal_notification_rules.md

@@ -35,7 +35,7 @@ The above command returns JSON structured in the following way:
 | ----------- | :------: | :-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
 | `user_id`   |   Yes    | User ID                                                                                                                                                                                                                                                                                             |
 | `position`  | Optional | Personal notification rules execute one after another starting from `position=0`. `Position=-1` will put the escalation policy to the end of the list. A new escalation policy created with a position of an existing escalation policy will move the old one (and all following) down on the list. |
-| `type`      |   Yes    | One of: `wait`, `notify_by_slack`, `notify_by_sms`, `notify_by_phone_call`, `notify_by_telegram`, `notify_by_email`, `notify_by_mobile_app`, `notify_by_mobile_app_critical`.                                                                                                                                                                                |
+| `type`      |   Yes    | One of: `wait`, `notify_by_slack`, `notify_by_sms`, `notify_by_phone_call`, `notify_by_telegram`, `notify_by_email`, `notify_by_mobile_app`, `notify_by_mobile_app_critical`, or `notify_by_msteams` (**NOTE** `notify_by_msteams` is only available on Grafana Cloud).                                                                                                                                                                                |
 | `duration`  | Optional | A time in seconds to wait (when `type=wait`). Can be one of 60, 300, 900, 1800, or 3600.                                                                                                                                                                                                                                               |
 | `important` | Optional | Boolean value indicates if a rule is "important". Default is `false`.                                                                                                                                                                                                                               |
 

engine/apps/alerts/tasks/notify_user.py

@@ -81,10 +81,12 @@ def notify_user_task(
 
             # Here we collect a brief overview of notification steps configured for user to send it to thread.
             collected_steps_ids = []
-            for notification_policy in notification_policies:
-                if notification_policy.step == UserNotificationPolicy.Step.NOTIFY:
-                    if notification_policy.notify_by not in collected_steps_ids:
-                        collected_steps_ids.append(notification_policy.notify_by)
+            for next_notification_policy in notification_policies:
+                if next_notification_policy.step == UserNotificationPolicy.Step.NOTIFY:
+                    if next_notification_policy.notify_by not in collected_steps_ids:
+                        collected_steps_ids.append(next_notification_policy.notify_by)
+
+            notification_policy = notification_policies[0]
 
             collected_steps = ", ".join(
                 UserNotificationPolicy.NotificationChannel(step_id).label for step_id in collected_steps_ids