[Merge] lp:~xnox/ubuntu-archive-publishing/migrate-dist-upgrade-to-4k into lp:ubuntu-archive-publishing

[Dimitri John Ledkov]

Encoded all ubuntu) digests into the command lines, and updated comments to match that we are encoding digests in the code from now on.

Hopefully, the transition to 8k key with SHA-3 digest algo will go more smooth.
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https://code.launchpad.net/~xnox/ubuntu-archive-publishing/migrate-dist-upgrade-to-4k/+merge/311181
Your team Ubuntu Package Archive Administrators is requested to review the proposed merge of lp:~xnox/ubuntu-archive-publishing/migrate-dist-upgrade-to-4k into lp:ubuntu-archive-publishing.