ibusManager: Avoid changes to ibus-typing-booster configuration

ibusManager: Avoid changes to ibus-typing-booster configuration

The ibus-typing-booster IM module is already meant to do the "right"
thing when the IBus.Capabilite.OSK hint is passed to the IM. We do
already honor that hint (commit 23bfd08b3c9), and ibus-typing-booster
has been doing this for a reasonably long time (first release seems
to be 2.19.9 dated 2 years ago, current is 2.24.12).

Drop this mangling of foreign settings, and let ibus-typing-booster
figure out the optimal configuration given the presence of an OSK.

Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/3162>