tools: Remove absolute_import in most tools.

Tweaked by tabbott to not remove it from lister.py, linter_lib, and
friends, since those are intended to support both Python 2 and 3
(we're planning to extract them from the repository).

tools/run-dev-queue-processors

@@ -5,7 +5,6 @@
 # separate script so that the import from zerver.worker.queue_processors (which
 # is slow) can be done in parallel with the rest of the work in bringing up the
 # dev server.
-from __future__ import absolute_import
 import sys
 import os
 import subprocess