Deal with Tails Installer' urlgrabber embedded copy

A bunch of tails_installer/urlgrabber/*.py have different copyright and licensing info than the rest of Tails Installer. That’s not documented in debian/copyright, so the package was rightfully rejected by ftp-masters.

Moreover, these files seem to be some old (possibly modified) version of the code that’s shipped in the python-urlgrabber Debian package, so they would be embedded code copies, that are frowned upon in Debian.

Either we should remove these files (that are not used right now) from Git, or we should not ship them in the released tarballs, or in the DFSG-ed tarball.

Parent Task: #8549 (closed)

Related issues

Blocks #8557 (closed)

Original created by @intrigeri on 10692 (Redmine)

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