The repo is Python 3 now, so update hacking to version 3.0 which
supports Python 3.
Fix problems found.
Update local hacking checks for new flake8.
Remove hacking and friends from lower-constraints, it's not needed
there.
Change-Id: I48fcd2521d99d0b77b976e87cc638fe5ac051315
The i18n team has decided not to translate the logs because it seems
like it not very useful; operators prefer to have them in English so
that they can search for those strings on the internet.
Since we have removed log translations completely, we should add hacking
rule to prevent future mistakes.
Change-Id: Ia7524308ef2675f8d41ac80b37dfc7e3787efd90