🍒 Only chop off leading @ from tokenized license text if needed

Apparently at some point in the past, tokenized non-SPDX license labels got prefixed with "@". As a result, the code unconditionally chopped off the first character.

At some point, tokenizing stopped always doing that, causing some license labels to be shown with their first letter missing.

I don't know if the prepending might come back in the future, so to be safe, let's only conditionally remove the first character if it's "@".

BUG: 491172 FIXED-IN: 6.1.4

(cherry picked from commit 1b9b314a)

Co-authored-by: Nate Graham nate@kde.org