Other Software shows extra entry for Ubuntu distribution repository

[Jeremy Bícha]

Test Case
---------
- Open the Software & Updates tab
- Switch to the Other Software tab

There is an entry for
## Ubuntu distribution repository
##
## The following settings can be adjusted to configure which packages to use from Ubuntu.

etc.

What I Expected
---------------
That entry should not show. Selecting the entry and clicking Edit allows adjusting the main Ubuntu repository source settings which should not be allowed there since it is already possible to do that from the Ubuntu Software tab.

ProblemType: Bug
DistroRelease: Ubuntu 24.04
Package: software-properties-gtk 0.99.44
ProcVersionSignature: Ubuntu 6.8.0-20.20-generic 6.8.1
Uname: Linux 6.8.0-20-generic x86_64
NonfreeKernelModules: zfs
ApportVersion: 2.28.0-0ubuntu1
Architecture: amd64
CasperMD5CheckResult: pass
CurrentDesktop: ubuntu:GNOME
Date: Fri Mar 29 12:10:24 2024
InstallationDate: Installed on 2022-04-06 (723 days ago)
InstallationMedia: Ubuntu 22.04 LTS "Jammy Jellyfish" - Daily amd64 (20220405)
PackageArchitecture: all
ProcEnviron:
 LANG=en_US.UTF-8
 PATH=(custom, no user)
 SHELL=/bin/bash
 TERM=xterm-256color
 XDG_RUNTIME_DIR=<set>
SourcePackage: software-properties
UpgradeStatus: Upgraded to noble on 2023-12-09 (111 days ago)

[Launchpad Janitor (janitor)]

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

[Nathan Teodosio (nteodosio)]

I split the issue about the too many comments to LP:2060915.