tools: make test-npm work without global npm

Futher discussion at https://github.com/joyent/node/pull/25294

PR-URL: https://github.com/nodejs/io.js/pull/1926
Reviewed-By: Rod Vagg <rod@vagg.org>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>

tools/test-npm.sh

@@ -30,7 +30,8 @@ export npm_config_tmp="npm-tmp"
 
 # install npm devDependencies and run npm's tests
 ../$NODE_EXE cli.js install --ignore-scripts
-../$NODE_EXE cli.js run-script test-all
+../$NODE_EXE cli.js run-script test-legacy
+../$NODE_EXE cli.js run-script test
 
 # clean up everything one single shot
 cd .. && rm -rf test-npm