Disabling AMQP requests with "ADT_ENABLE = yes" but ADT_AMQP unset made sense
while we still supported adt-britney. But as that's gone now, let's use the
ADT_ENABLE switch only, and if it's on, require ADT_AMQP and ADT_SWIFT_URL be
set.
This simplifies the code a bit and is less confusing.
Their default values are invalid and must be set locally. But as
britney1-ubuntu copies these into production, we would run with an invalid
config with an unmodified config file.
Until now, autopkgtest results were triggered via an external "adt-britney"
command from lp:auto-package-testing. This required a lot of state files and
duplicated effort, uses hardcoded absolute paths to these external tools, and
is quite hard to understand and maintain. We also want to move away from
Jenkins and rsyncing state files.
Directly retrieve autopkgtest results from a publicly readable and browsable
Swift container, with a debci-compatible layout
(https://wiki.debian.org/debci/DistributedSpec). This now tracks both requests
and results on a per-architecture granularity, so that we can track
per-architecture regressions/always-failed.
Introduce a new ADT_SWIFT_URL config option that sets the swift base URL. If
this key is not set, the behaviour does not change compared to previous
versions, and no results will be retrieved from the cloud.
This still keeps the old adt-britney requests/results as the authoritative
data and for now merely shows the swift results in addition. With that we can
compare the results and run the cloud testing in parallel to find/fix problems
until we switch over. Due to that, the code to britney.py is temporary, does
*not* use AutoPackageTest.results(), and instead just reads the internal
results map.
