main/postmarketos-ui-gnome: don't install gnome-mobile forks

main/postmarketos-ui-gnome: don't install gnome-mobile forks

Don't install the experimental gnome-mobile forks of gnome-shell and
mutter in regular GNOME. These are probably more stable, and most
importantly this prevents accidental uninstallation of gnome-shell
without installing gnome-mobile-shell.

Revert the addition of the gnome-shell dependency to
postmarketos-ui-gnome. This isn't needed anymore and caused further
issues.

main/postmarketos-ui-phosh: don't install gnome-mobile forks

There is no need to install the experimental GNOME mobile forks when
running Phosh, it will probably just cause instabilities. Let's rather
not do it.

Fixes: #1701 (closed)