community/phosh: execute squeekboard directly instead of going through osk-wayland

I am not sure what the point of this ever was. In Alpine, osk-wayland does not exist. Downstream in postmarketOS it is a script that checks for the presence of squeekboard and then executes squeekboard, and if it does not exist, it defaults to virtboard which as far as I can tell never existed in Alpine and has long been dropped from postmarketOS. As such, do away with this needless indirection and execute squeekboard directly.