Merge "Rename btu_task.h -> main_thread.h" into main am: 6a1ff548 am: 6f67790d

Original change: https://android-review.googlesource.com/c/platform/packages/modules/Bluetooth/+/2786431



Change-Id: I0f1737e796fc17873d71111c5d9746fabc00e3f6
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>