Gardening: Fix the `begin` lines in many of the uuencoded test data (#2043)

Gardening: Fix the `begin` lines in many of the uuencoded test data (#2043)

The libarchive test harness always extracts these to the truncated
source filename, ignoring the name in the `begin` line. However, for
ease of experimentation, people will want to manually extract these with
`uudecode`, so the `begin` lines should have the correct filename.