Do not show error toast when received UNBOND_REASON_REMOVED

Do not show error toast when received UNBOND_REASON_REMOVED,
because this reason is also received when devices unbond
like forget devices.

Bug: 181738217
Bug: 173165769
Test: make -j42 RunSettingsLibRoboTests
Change-Id: I7c9675014bb642a28dcfb313fa5ce7283cb43d92