Update adb command to remove all configs from statsd

Before this change we were only clearing configs from disk.
This change will allow clearing from memory as well. Also,
this change fixes a bug where the iterator moves to the next
element before removing the key from mConfigReceivers

Test: statsd, statsd_test

Change-Id: I9f5e0aced9b89bae7b19ae6d8490c076557fbb08