Keyboard shortcut Super+Alt+Up is hardcoded to show activities overview

[Heewa Barfchin]

### Affected version

Ubuntu 21.10 (dev), Wayland, Gnome 40.2.0, gnome-shell 40.2-1ubuntu1

### Bug summary

The keyboard shortcut `Super+Alt+Up` seems to be hardcoded to something along the lines of showing activities overview, and cannot be removed or used for any other action, even if it's shown as assigned to one.

### Steps to reproduce

1. Open system preferences, and navigate to Keyboard -> Keyboard Shortcuts -> Customize Shortcuts -> System
2. Verify that no action has `Super+Alt+Up` set, removing/changing any actions if it's already assigned.
3. Optional: assign `Super+Alt+Up` to some other action.
4. Press `Super+Alt+Up`

### What did you expect to happen

Either the action which `Super+Alt+Up` is shown to be assigned to, or nothing if no action has that shortcut assigned.

### What happened

The activities overview is shown.

### Upstream bug report

https://gitlab.gnome.org/GNOME/gnome-shell/-/issues/4497 - maintainers indicated this is most likely cause by a downstream modification.

ProblemType: Bug
DistroRelease: Ubuntu 21.10
Package: gnome-shell 40.2-1ubuntu1
ProcVersionSignature: Ubuntu 5.11.0-20.21+21.10.1-generic 5.11.21
Uname: Linux 5.11.0-20-generic x86_64
ApportVersion: 2.20.11-0ubuntu67
Architecture: amd64
CasperMD5CheckResult: unknown
CurrentDesktop: ubuntu:GNOME
Date: Fri Jul 23 12:54:57 2021
DisplayManager: gdm3
GsettingsChanges:

InstallationDate: Installed on 2019-11-17 (614 days ago)
InstallationMedia: Ubuntu 19.10 "Eoan Ermine" - Release amd64 (20191017)
RelatedPackageVersions: mutter-common 40.2.1-1ubuntu1
SourcePackage: gnome-shell
UpgradeStatus: No upgrade log present (probably fresh install)

_Edit: fix `Super+Up`-> `Super+Alt+Up`_

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Daniel van Vugt (vanvugt)]

Thank you for reporting this bug to Ubuntu.

Ubuntu 21.10 (impish) reached end-of-life on July 14, 2022.

See this document for currently supported Ubuntu releases:
https://wiki.ubuntu.com/Releases

We appreciate that this bug may be old and you might not be interested in discussing it any more. But if you are then please upgrade to the latest Ubuntu version and re-test. If you then find the bug is still present in the newer Ubuntu version, please add a comment here telling us which new version it is in.