Add full avatar URL for on-call users in schedule internal API (#2414)

# What this PR does

Adds full avatar URL for on-call users in schedule internal API
(`avatar_full`).

## Checklist

- [x] Unit, integration, and e2e (if applicable) tests updated
- [x] Documentation added (or `pr:no public docs` PR label added if not
required)
- [x] `CHANGELOG.md` updated (or `pr:no changelog` PR label added if not
required)

CHANGELOG.md

@@ -5,6 +5,12 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## Unreleased
+
+### Added
+
+- Add full avatar URL for on-call users in schedule internal API by @vadimkerr ([#2414](https://github.com/grafana/oncall/pull/2414))
+
 ## v1.3.3 (2023-06-29)
 
 ### Added

engine/apps/api/tests/test_schedules.py

@@ -1858,3 +1858,36 @@ def test_get_schedule_from_other_team_with_flag(
 
     response = client.get(url, format="json", **make_user_auth_headers(user, token))
     assert response.status_code == status.HTTP_200_OK
+
+
+@pytest.mark.django_db
+def test_get_schedule_on_call_now(
+    make_organization, make_user_for_organization, make_token_for_organization, make_schedule, make_user_auth_headers
+):
+    organization = make_organization(grafana_url="https://example.com")
+    user = make_user_for_organization(organization, username="test", avatar_url="/avatar/test123")
+    _, token = make_token_for_organization(organization)
+
+    schedule = make_schedule(
+        organization,
+        schedule_class=OnCallScheduleWeb,
+        name="test_web_schedule",
+    )
+
+    client = APIClient()
+    url = reverse("api-internal:schedule-list")
+    with patch(
+        "apps.schedules.models.on_call_schedule.OnCallScheduleQuerySet.get_oncall_users",
+        return_value={schedule.pk: [user]},
+    ):
+        response = client.get(url, format="json", **make_user_auth_headers(user, token))
+
+    assert response.status_code == status.HTTP_200_OK
+    assert response.json()["results"][0]["on_call_now"] == [
+        {
+            "pk": user.public_primary_key,
+            "username": "test",
+            "avatar": "/avatar/test123",
+            "avatar_full": "https://example.com/avatar/test123",
+        }
+    ]

engine/apps/user_management/models/user.py

@@ -270,7 +270,12 @@ class User(models.Model):
         self._timezone = value
 
     def short(self):
-        return {"username": self.username, "pk": self.public_primary_key, "avatar": self.avatar_url}
+        return {
+            "username": self.username,
+            "pk": self.public_primary_key,
+            "avatar": self.avatar_url,
+            "avatar_full": self.avatar_full_url,
+        }
 
     # Insight logs
     @property