npm cache clean is not a good idea in the artifact build

tools/run_tests/build_artifact_node.bat

@@ -33,7 +33,6 @@ set PATH=%PATH%;C:\Program Files\nodejs\;%APPDATA%\npm
 
 del /f /q BUILD || rmdir build /s /q
 
-call npm cache clean || goto :error
 call npm update || goto :error
 
 mkdir artifacts

tools/run_tests/build_artifact_node.sh

@@ -40,7 +40,6 @@ rm -rf build || true
 
 mkdir -p artifacts
 
-npm cache clean
 npm update
 
 node_versions=( 0.12.0 1.0.0 1.1.0 2.0.0 3.0.0 4.0.0 5.0.0 6.0.0 )