[Chipbar] Have MediaTttSenderCoordinator be responsible for not hiding

in certain cases.

Bug: 245610654
Test: manual: Send a TRANSFER_TRIGGERED event then FAR_FROM_RECEIVER
event and verify the chip is still displayed (i.e. the removal request
is ignored)
Test: manual: Send a ALMOST_CLOSE event then FAR_FROM_RECEIVER event and
verify the chip is hidden
Test: atest MediaTttSenderCoordinatorTest
Test: atest ChipbarCoordinatorTest
Change-Id: I8cd33a65ec48f37aa83179b348f60916df3990a8

Change-Id: Ic1f1d2fcb09727ebc24d649a26dcea40ca8287b2