Hello I have found a solution now. after very much headache.
I just found out the version of Cordova AdMob plugin (cordova-plugin-ad-admob) is update to 1.0.117
and my old project that Admob is working fine is 1.0.112
so I remove the 1.0.117 and change to 1.0.112 and lucky it work. no Admob test mode now.
I think it bugs from cordova-plugin-ad-admob v 1.0.117 that always run in test mode. someone should tell the developer to fixed this bugs.