Unrecognized parameter "append_to" when an extension tries to construct an animated icon

[Mark Jaroski]

This bug has been reported to the extension developer here:

https://github.com/2nv2u/gnome-shell-extension-syncthing-indicator/issues/39

It appears that some upstream Gnome change which the extension developer tracked and compensated for in their recent Gnome 46 compatibility release did not make the cut for the 24.04 Ubuntu release.

```
Description: Ubuntu 24.04 LTS
Release: 24.04
```

```
$ apt-cache policy gnome-shell
gnome-shell:
  Installed: 46.0-0ubuntu5.1
  Candidate: 46.0-0ubuntu5.1
  Version table:
 *** 46.0-0ubuntu5.1 500
        500 http://ch.archive.ubuntu.com/ubuntu noble-updates/main amd64 Packages
        500 http://security.ubuntu.com/ubuntu noble-security/main amd64 Packages
        100 /var/lib/dpkg/status
     46.0-0ubuntu5 500
        500 http://ch.archive.ubuntu.com/ubuntu noble/main amd64 Packages
```

Expected: the extension should load and run as in other Gnome 46 distributions

What happened instead: the extension throws an error, which interestingly is not caught by the extension manager, but is at least reported.

Stack trace from the upstream error report in GitHub:
```
Stack trace:
                                            parse@resource:///org/gnome/shell/misc/params.js:24:23
                                            _init@resource:///org/gnome/shell/ui/animation.js:20:25
                                            Animation@resource:///org/gnome/shell/ui/animation.js:17:1
                                            SyncthingPanelIcon@file:///<email address hidden>/extension>
                                            _init@file:///<email address hidden>/extension.js:456:15
                                            ButtonBox@resource:///org/gnome/shell/ui/panelMenu.js:12:1
                                            PanelMenuButton@resource:///org/gnome/shell/ui/panelMenu.js:97:4
                                            SyncthingIndicator@file:///<email address hidden>/extension>
                                            enable@file:///<email address hidden>/extension.js:546:20
                                            _callExtensionEnable@resource:///org/gnome/shell/ui/extensionSystem.js:267:38
                                            loadExtension@resource:///org/gnome/shell/ui/extensionSystem.js:479:32
                                            async*_loadExtensions@resource:///org/gnome/shell/ui/extensionSystem.js:795:24
                                            async*_enableAllExtensions@resource:///org/gnome/shell/ui/extensionSystem.js:801:48
                                            _sessionUpdated@resource:///org/gnome/shell/ui/extensionSystem.js:836:20
                                            async*init@resource:///org/gnome/shell/ui/extensionSystem.js:77:14
                                            _initializeUI@resource:///org/gnome/shell/ui/main.js:313:22
                                            start@resource:///org/gnome/shell/ui/main.js:185:11
                                            @resource:///org/gnome/shell/ui/init.js:12:47
                                            @resource:///org/gnome/shell/ui/init.js:21:20
```

[Daniel van Vugt (vanvugt)]

I'm not sure gnome-shell is doing anything wrong here so let's keep it upstream for now: https://github.com/2nv2u/gnome-shell-extension-syncthing-indicator/issues/39