core22 "20250210" causes plymouth-show-run.service failure on rpi2

To reproduce:
1. Provision a rpi2 with `http://cdimage.ubuntu.com/ubuntu-core/22/dangerous-stable/pending/ubuntu-core-22-armhf+raspi.img.xz`
2. Switch core22 to beta `sudo snap refresh --channel latest/beta` then wait for reboot
3. Look at failing services `sudo systemctl list-units --failed` and observe that `plymouth-show-run.service` failed

Logs:
```
$ sudo systemctl list-units --failed
UNIT LOAD ACTIVE SUB DESCRIPTION
● plymouth-show-run.service loaded failed failed Display state on splash

LOAD = Reflects whether the unit definition was properly loaded.
ACTIVE = The high-level unit activation state, i.e. generalization of SUB.
SUB = The low-level unit activation state, values depend on unit type.
1 loaded units listed.
```
```
$ sudo journalctl --unit plymouth-show-run.service
Feb 19 09:28:05 ubuntu systemd[1]: Starting Display state on splash...
Feb 19 09:28:25 ubuntu systemd[1]: plymouth-show-run.service: start operation timed out. Terminating.
Feb 19 09:28:25 ubuntu systemd[1]: plymouth-show-run.service: Failed with result 'timeout'.
Feb 19 09:28:25 ubuntu systemd[1]: Failed to start Display state on splash.
```

Reproduce on an rpi2 using the linked Ubuntu Core 22 image, switch core22 to latest/beta, and inspect plymouth-show-run.service with systemctl and journalctl. Trace the timeout and verify that the service starts successfully after the relevant core22 change.

Written by the indexing model from the issue text.