Fix AIDL sensors VTS test

- According to the AIDL backends, return values are not propagated
  when the status is !ok(). Update the VTS test, HAL implementation,
  and ISensors definition to remove the requirement that the
  handle is populated to -1 on failure for registerDirectChannel.
- Also update VTS tests for some error code checks to reflect the
  actual expecataions according to the ISensors documentation.

Bug: 228645167
Test: VTS passes
Change-Id: I5d4d4d0af3b033b34a58d8462aa40214d89fa442