Sync Jenkins config

Summary:
Notable changes:

  * Number of executors increased from 2 -> 3.
  * deploy-daily now sets FORCE_INDEX_CHANGES by default.
  * update-translations now keeps 5 days of temporary build files.
  * Removed code coverage from website-commit and website-allcheck.
  * webapp/tools/build-make-target.sh takes make args directly.

Test Plan: This config is already running live.

Reviewers: csilvers

Reviewed By: csilvers

Differential Revision: http://phabricator.khanacademy.org/D4705