Prevent stock OTA activities from running in CM

Change-Id: I3f586cd246fc351afb82c94f41329bf930f6f41a
otablock: Disable only the actual activity, leave the service on

This is apparently shutting down uncleanly and frequently leaving
unwanted stuff active :(

Change-Id: I08e7b28adf1ec0725b82357df96beda2527e2f16