add hello_world__memory test to devicelab (#7143)
add hello_world__memory test to devicelab (#7143)


Hixie/flutter,flutter/flutter,cbracken/flutter,flutter/flutter,cbracken/flutter,cbracken/flutter,cbracken/flutter,flutter/flutter,cbracken/flutter,turnidge/flutter,turnidge/flutter,flutter/flutter,cbracken/flutter,turnidge/flutter,tvolkert/flutter,tvolkert/flutter,flutter/flutter,flutter/flutter,flutter/flutter,Hixie/flutter,Hixie/flutter,turnidge/flutter,Hixie/flutter,tvolkert/flutter,tvolkert/flutter,tvolkert/flutter,flutter/flutter,cbracken/flutter,tvolkert/flutter,flutter/flutter,Hixie/flutter,tvolkert/flutter,Hixie/flutter,cbracken/flutter,turnidge/flutter,tvolkert/flutter,tvolkert/flutter,Hixie/flutter,cbracken/flutter,flutter/flutter,tvolkert/flutter,Hixie/flutter,Hixie/flutter,cbracken/flutter,Hixie/flutter