Skip zip regeneration when user didn't provide extra info.

If the user provides a title or description, it's necessary to create a
new zip file with the contents of the old file plus the new entries,
which takes time.

Hence, if the user didn't provide more info (title or description), we
should skip that step.

BUG: 26616935
Change-Id: Ice14f88b5763d463d8db2f942e823797e80bfde9