in DorisAndroidPrefetch/libs

we have a bunch of jars files that are completly out of date. (9 years old !)

in addition this is a bad practice to copy that in the project, we should use explicit gradle dependencies so the tooling may raise upgrade suggestions.

hopefully this is mainly for the prefetch app and not the deployed android app (there is only a couple of jars in the libs folder of DorisAndroidCommons)