[ADI] add a command to clear previously set local experiments

Adding this command so that the user can clear the previously set
experiment for a package. Otherwise the user will have to wait for the
timeout which is inconvenient. This command can also be used in
automated testing for improving test robustness.

BUG: 399436145
Test: manually
FLAG: android.content.pm.verification_service

Change-Id: I5bb0a6570e50efd9e47286c025da23734e94a06f