[FIX] mail: inverts the zoom scroll direction of the attachment viewer

This commit inverts the zoom direction of the scroll wheel in the
attachment viewer to respect the behaviour of before the refactor.

part of task-2171884

closes odoo/odoo#60009

X-original-commit: 3d9e2e031ea2e92a50769cc69fe37741d32b6820
Signed-off-by: Alexandre Kühn (aku) <aku@odoo.com>

addons/mail/static/src/components/attachment_viewer/attachment_viewer.js

@@ -573,9 +573,9 @@ class AttachmentViewer extends Component {
             return;
         }
         if (ev.deltaY > 0) {
-            this._zoomIn({ scroll: true });
-        } else {
             this._zoomOut({ scroll: true });
+        } else {
+            this._zoomIn({ scroll: true });
         }
     }