Warning on startup: [qt.qpa.services] Failed to register with host portal QDBusError("org.freedesktop.portal.Error.Failed", "Could not register app ID: App info not found for 'com.github.hluk.copyq'")

**Describe the bug**
Every time CopyQ starts, a warning is logged.

**To Reproduce**
1. Start CopyQ (from the command line)

**Expected behavior**
No warning is displayed or logged.

**Actual behavior**

> $ ./CopyQ-*.AppImage
> Warning: [qt.qpa.services] Failed to register with host portal QDBusError("org.freedesktop.portal.Error.Failed", "Could not register app ID: App info not found for 'com.github.hluk.copyq'")

**Version, OS and Environment**
CopyQ 16.0.0
Arch: x86_64-little_endian-lp64
Audio: miniaudio 0.11.25
Compiler: GCC
DISPLAY: :0
KGuiAddons: 6.27.0
KNotifications: 6.27.0
KStatusNotifierItem: 6.27.0
OS: Debian GNU/Linux 13 (trixie)
QCA: 2.3.10
Qt: 6.11.1
QtKeychain: 0.15.0
XDG_CURRENT_DESKTOP: KDE
XDG_SESSION_DESKTOP: KDE
XDG_SESSION_TYPE: x11
has-audio: 1
has-encryption: 1
has-global-shortcuts: 1
has-keychain: 1
has-mouse-selection: 1

**Additional context**
Logs provided by @WillTest in ticket #3488 and @robertstrom in #3587 contain a similar error:

> Warning <[...]>: [qt.qpa.services] Failed to register with host portal QDBusError("org.freedesktop.portal.Error.Failed", "Could not register app ID: Connection already associated with an application ID")

In the install I tested the most though, I cannot see any behavioral defect from superficial testing (besides the probably unrelated performance issue tracked in #3634).

This affects 2 PCs running CopyQ 16 on Debian 13 out of 2 tested. I could not reproduce with CopyQ 10 though.

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