[Merge] ~cpete/ubuntu-dev-tools:add-running-autopkgtests into ubuntu-dev-tools:main

[Chris Peterson]

I added some comments in the tests to be clear they are running off of cached data, updated the help description a bit, and rebased off the new main branch.
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https://code.launchpad.net/~cpete/ubuntu-dev-tools/+git/ubuntu-dev-tools/+merge/459002
Your team Ubuntu Development Team is requested to review the proposed merge of ~cpete/ubuntu-dev-tools:add-running-autopkgtests into ubuntu-dev-tools:main.