Fix ANR due to `updateShortcuts` called in the main thread

* `updateShortcuts` is an IPC call;
* In a rare case, the SystemUI did not have much resources which made
 the IPC call take time to complete - that caused an ANR;
* To avoid such situation, where offloading the IPC call to out the main
 thread;

Test: atest NoteTaskControllerTest
Flag: not needed
Fixes: b/298003843
Change-Id: Ifff2e2fed94d4c05c0733c9215fa4e96fab090c9