archiver: tests: resolve potential source of flakiness

archiver: tests: resolve potential source of flakiness

Increase all timeouts to 10 seconds; these aren't hard-coded sleeps, so
there's no guarantee we'll actually take that long. If we need longer to
not have a false-positive, then so be it.

While here, various assert.{Not,}Equal arguments are flipped around so that
the wording in error output reflects reality, where the expected argument is
second and actual third.