Revert "Changed dpm shell commands to use 'cmd device_policy'"

This reverts commit e311f273.

Reason for revert: Suspected to break git_sc-dev: https://android-build.googleplex.com/builds/tests/view?invocationId=I95100008561539923&testResultId=TR98321419962361792

Bug: 186208038
Change-Id: I0dc3ee2d509f395677600590d0cbb42b4d9f1682