lib,test: use consistent operator linebreak style

We have a tacit rule that for multiline statements, the operator should
be placed before the linebreak. This commit commit fixes the few
violations of this rule in the code base.
This allows us to enable the corresponding ESLint rule.

PR-URL: https://github.com/nodejs/node/pull/10178


Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Roman Reiss <me@silverwind.io>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Jeremiah Senkpiel <fishrock123@rocketmail.com>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Teddy Katz <teddy.katz@gmail.com>
Reviewed-By: Sakthipriyan Vairamani <thechargingvolcano@gmail.com>