Add separate command executor test file for config subcommand

- perfetto_command_executor_unit_test runs its tests and the tests for
  the config subcommand, which is misleading. Add a separate test file
  for config unit tests.
- Update the relevant tests.

Test: ./torq_test
Flag: EXEMPT refactor
Bug: 383371656
Change-Id: I08fb2a74037c1440561eea7cfb0b49bdb26418ba
3 files changed