VtsHalBluetoothTargetTest: Remove SCO loopback tests

SCO over HCI is not an explicit VSR requirement
of the Android Bluetooth stack as SCO streams
are always offloaded.

Bug: 352247861
Bug: 297818112
Test: atest VtsHalBluetoothTargetTest
Change-Id: Id6fcec230e07897cb63c80eada47c9c58a869c73
(cherry picked from commit 13a74787)