gd: gd/hci/le_address_manager_test::ASSERT_LOG when command queue is empty

Returning an empty vector causes debug headaches

Bug: 171568335
Test: CtsVerifier
Test: gd/cert/run --host
Test: atest --host bluetooth_test_gd
Tag: #refactor
Change-Id: I9d5f2ecacfe2bbcea7a333d3701523a6d9cfcaae