test: refactor common.js

* remove unused common.faketimeCli
* remove mosly-unused common.testDir
* assert.ok(false...) -> fail()
* alphabetize list of known globals
* .indexOf() -> .includes()

PR-URL: https://github.com/nodejs/node/pull/9732


Reviewed-By: Santiago Gimeno <santiago.gimeno@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Jeremiah Senkpiel <fishrock123@rocketmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>