fix: --print-uris removes authentication

The constructors of our (clear)sign-acquire-items move a pre-existent
file for error-recovery away, which gets restored or discarded later as
the acquire progresses, but --print-uris never really starts the
acquire process, so the files aren't restored (as they should).

To fix this both get a destructor which checks for signs of acquire
doing anything and if it hasn't the file is restored.

Note that these virtual destructors theoretically break the API, but
only with classes extending the sign-acquire-items and nobody does this,
as it would be insane for library users to fiddle with Acquire
internals – and these classes are internals.

Closes: 719263