Order imports in alphabetical order (3/9)

This patch is one in a series to re-enable H306 style check rule
(imports are in alphabetical order). It touches common and cloudinit files.

Implements: blueprint reduce-flake8-ignored-rules (partial)
Change-Id: Ie9838dba11323575165fc3bfdfbd0d0b93f653fa
Merge "Order imports in alphabetical order (3/9)"