seeding a package that depends/recommends fuse3 causes livefs builds to fail

Seeding a package that depends/recommends fuse3 causes livefs builds to fail.

Examples:

kio-fuse: depends fuse3. Upstream KDE have requested/suggested that KDE distro add this to their default install.

sshfs-fuse: a dependency of kdeconnect, which is a default recommends in Kubuntu. Currently the version in Ubuntu is 3.6.0+repack+really2.10-0ubuntu1 as the real 3.x release from debian depends now on fuse3, and so breaks ISO builds.

Example build failure with seeded kio-fuse: https://launchpad.net/~ubuntu-cdimage/+livefs/ubuntu/hirsute/kubuntu/+build/261723

**** build log snip ****

Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
 fuse3 : Breaks: fuse
E: Unable to correct problems, you have held broken packages.
P: Begin unmounting filesystems...
P: Saving caches...
P: Begin unmounting filesystems...
P: Saving caches...
Build failed
Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/lpbuildd/target/build_livefs.py", line 176, in run
    self.build()
  File "/usr/lib/python3/dist-packages/lpbuildd/target/build_livefs.py", line 167, in build
    self.run_build_command(["lb", "build"], env=base_lb_env)
  File "/usr/lib/python3/dist-packages/lpbuildd/target/build_livefs.py", line 90, in run_build_command
    return self.backend.run(args, cwd="/build", **kwargs)
  File "/usr/lib/python3/dist-packages/lpbuildd/target/lxd.py", line 537, in run
    subprocess.check_call(cmd, **kwargs)
  File "/usr/lib/python3.6/subprocess.py", line 311, in check_call
    raise CalledProcessError(retcode, cmd)
subprocess.CalledProcessError: Command '['lxc', 'exec', 'lp-hirsute-amd64', '--env', 'PROJECT=kubuntu', '--env', 'ARCH=amd64', '--', '/bin/sh', '-c', 'cd /build && linux64 lb build']' returned non-zero exit status 1.