Windows machines are changing language / keyboard layout to Welsh

[sxa]

Seen on some of the Windows 2019 and 2022 machines while investigating #3556

The machines seem to be switching themselves to Welsh (CYM). The language doesn't show as being installed on the machine and therefore cannot be removed. The fix is to install and remove it, but it seems to come back on a reboot.

Unclear what is causing this - maybe one of the language tests? Although in that situation I would not expect it to take effect for all users.