main/postmarketos-ui-{lxqt|mate}: issues with font-droid
<!--
Thank you for using postmarketOS! In order to speed up process of resolving your issue,
we would like you to fill in the following form.
*** NOTE FOR CONFIDENTIAL ISSUES: ***
A lot of people can read confidential pmaports issues! If you want to
submit something that only the postmarketOS Core Team can see, write to
team@postmarketos.org
instead of opening an issue here!
-->
### Describe your issue
#### What's the expected behaviour?
Usual font on virtual keyboard and in terminal application.
#### What's the current behaviour?
MR !5540 removed `font-dejavu` and added `font-droid`. In user interfaces LXQt and MATE there is now a Unicode BMP fallback glyph of character U+23CE (return symbol) on the return key of `onboard` virtual keyboard and the font in the terminal looks strange.
Picture of LXQt:

Picture of MATE:

I tried to "repair" the fonts in GUI settings or by terminal commands but couldn't find a solution yet. Actually I tend to add package `font-dejavu` to `postmarketos-ui-lxqt` and `postmarketos-ui-mate`. Maybe someone has a better idea or knows how to get `font-droid` set up properly in LXQt and MATE.
Xfce4 doesn't show the problem because `font-dejavu` gets installed by Alpine package `xfce4`:
- https://gitlab.alpinelinux.org/alpine/aports/-/blob/2ea8f900538a20e55f13b176931bddd79871581b/community/xfce4/APKBUILD#L13
Cc: @omasanori
#### How to reproduce your issue?
E.g. a new installation using QEMU with pmbootstrap on a PC:
- pmbootstrap init
- channel: edge
- vendor: qemu
- device: amd64
- user interface: lxqt or mate
- pmbootstrap install
- pmbootstrap qemu
### What device are you using?
<!--
Leave name of your device in vendor-codename format.
If unsure, check name in the device package or leave full name of device
PinePhone: which revision exactly? See https://wiki.pine64.org/index.php/PinePhone#Hardware_revisions
-->
qemu-amd64
### On what postmarketOS version did you encounter the issue?
<!--
Replace space inside `[ ]` with `x` to fill the checkbox
-->
* [x] edge (`master` branch)
* [ ] `v24.06`
* [ ] I confirm that the issue still is present after running `sudo apk upgrade -a`
### On what environment did you encounter the issue?
#### Environments
* [ ] GNOME Shell on Mobile
* [ ] Phosh
* [ ] Plasma Mobile
* [ ] Sxmo (Wayland/Sway) **Please post the output of `sxmo_version.sh`**
* [x] Other: LXQt, MATE
### How did you get postmarketOS image?
* [ ] from https://images.postmarketos.org
* [x] I built it using pmbootstrap
* [ ] It was preinstalled on my device
### What's the build date of the image? (in yyyy-mm-dd format)
2024-09-25
<!--
Notes:
can be left empty if unsure
If you downloaded image from images.postmarketos.org, date will be in yyyymmdd format
-->
### Additional information
<!--
logs, etc. -- make use <details> for long listings
If your device displays an error message on boot or drops to the debug
shell, attaching it to your PC with a USB cable may show a removable USB
drive. You can drag and drop the .tar.gz file or otherwise upload it
here.
Refer to the README file on the device for more information.
-->
None
issue