OSF: Used model.NewPointer everywhere (#27838)

```release-note
NONE
```

server/channels/app/config_test.go

@@ -70,25 +70,25 @@ func TestEnsureInstallationDate(t *testing.T) {
 			Name:                     "New installation: no users, no installation date",
 			PrevInstallationDate:     nil,
 			UsersCreationDates:       nil,
-			ExpectedInstallationDate: model.NewInt64(utils.MillisFromTime(time.Now())),
+			ExpectedInstallationDate: model.NewPointer(utils.MillisFromTime(time.Now())),
 		},
 		{
 			Name:                     "Old installation: users, no installation date",
 			PrevInstallationDate:     nil,
 			UsersCreationDates:       []int64{10000000000, 30000000000, 20000000000},
-			ExpectedInstallationDate: model.NewInt64(10000000000),
+			ExpectedInstallationDate: model.NewPointer(int64(10000000000)),
 		},
 		{
 			Name:                     "New installation, second run: no users, installation date",
-			PrevInstallationDate:     model.NewInt64(80000000000),
+			PrevInstallationDate:     model.NewPointer(int64(80000000000)),
 			UsersCreationDates:       []int64{10000000000, 30000000000, 20000000000},
-			ExpectedInstallationDate: model.NewInt64(80000000000),
+			ExpectedInstallationDate: model.NewPointer(int64(80000000000)),
 		},
 		{
 			Name:                     "Old installation already updated: users, installation date",
-			PrevInstallationDate:     model.NewInt64(90000000000),
+			PrevInstallationDate:     model.NewPointer(int64(90000000000)),
 			UsersCreationDates:       []int64{10000000000, 30000000000, 20000000000},
-			ExpectedInstallationDate: model.NewInt64(90000000000),
+			ExpectedInstallationDate: model.NewPointer(int64(90000000000)),
 		},
 	}