Allow VTS of 1.0 tetheroffload to be optional

Per defined by compatibility matrixes, the tetheroffload
1.0 hardware is optional. But the tests failed if there
is no tetheroffload 1.0 hardware.
This is a regression during refactoring of the tests.

Test: atest VtsHalTetheroffloadControlV1_0TargetTest
Bug: 176057664
Change-Id: If54151beb3355b049b3f892f45c079cd5170d146