[CDM] Fix a bug where turning off Bluetooth before CDM BLE device discovery...

[CDM] Fix a bug where turning off Bluetooth before CDM BLE device discovery timeout results in a crash.

Bug: 427498880
Test: Manual test on CompanionDeviceTestApp (replaced with BLE scan)
Flag: EXEMPT bug fix
Change-Id: I48efc1279f7406b141d60d3931c7b61116c5c0f3