Code review comment for ~xnox/autopkgtest-cloud:all-proposed

This patch still applies, however, the comments seems still relevant to me. Is that feature still needed? If so, how do we progress forward? I can surely be of help writing code if need be, but as I understand, there are some design decisions to be taken, roughly:
* what parameters do we dump? All of them, only all-proposed, anything else? This is closely related to the data we have access to from `autopkgtest:runner/autopkgtest`, as we should probably aim at generating the same file in all situations.
* what about that privacy issue? I think there are some mechanisms for embargoed builds now, am I right?