Phosh already installs these schemas by default[1] and makes them specific
to the Phosh desktop. Originally these might have been needed because
either Phosh didn't ship the overrides or/and tinydm wasn't setting the
environment variable XDG_CURRENT_DESKTOP properly[2]. To verify that the
behavior of the Phosh override is working as expected one can do the following
from an ssh session (so that the full DE envvars are not set):
```bash
$ export DISPLAY=:0 # so that gsettings reset works
$ gsettings reset org.gnome.desktop.interface clock-show-date
$ gsettings get org.gnome.desktop.interface clock-show-date # false
$ sudo rm /usr/share/glib-2.0/schemas/000-postmarketos.gschema.override
$ sudo glib-compile-schemas --strict /usr/share/glib-2.0/schemas/
$ gsettings get org.gnome.desktop.interface clock-show-date # true (which is the default)
$ export XDG_CURRENT_DESKTOP=GNOME:Phosh
$ gsettings get org.gnome.desktop.interface clock-show-date # false (from phosh override)
```
[1] https://gitlab.gnome.org/World/Phosh/phosh/-/blob/main/data/00_sm.puri.Phosh.gschema.override
[2] https://gitlab.com/postmarketOS/tinydm/-/merge_requests/12
8fd97238fb