MM-32471: Use created user to update roles (#16895)

During user creation via CLI, we would create the user,
but pass the user ID instead when updating the roles.

This falls into the category of read-after-write within a single request.
We fix this by passing the already created user and
directly update the roles.

https://mattermost.atlassian.net/browse/MM-32471

```release-note
NONE
```

app/user.go

@@ -1547,6 +1547,11 @@ func (a *App) UpdateUserRoles(userID string, newRoles string, sendWebSocketEvent
 		return nil, err
 	}
 
+	return a.UpdateUserRolesWithUser(user, newRoles, sendWebSocketEvent)
+}
+
+func (a *App) UpdateUserRolesWithUser(user *model.User, newRoles string, sendWebSocketEvent bool) (*model.User, *model.AppError) {
+
 	if err := a.CheckRolesExist(strings.Fields(newRoles)); err != nil {
 		return nil, err
 	}
@@ -1586,7 +1591,7 @@ func (a *App) UpdateUserRoles(userID string, newRoles string, sendWebSocketEvent
 		mlog.Warn("Failed during updating user roles", mlog.Err(result.NErr))
 	}
 
-	a.InvalidateCacheForUser(userID)
+	a.InvalidateCacheForUser(user.Id)
 	a.ClearSessionCacheForUser(user.Id)
 
 	if sendWebSocketEvent {