Note that the upstream 91.5.0 release notes prominently say "For more on all the
new features in Thunderbird 91, see New in Thunderbird 91.0", and link to
https://support.mozilla.org/en-US/kb/new-thunderbird-91/, which seems much more
informative than
https://www.thunderbird.net/en-US/thunderbird/91.0/releasenotes/ for our
target audience.

So our users will still have a chance to get information about the 78 →
91 changes.

Upgrade Tor Browser to 11.0.6-build1

Closes #18799

See merge request tails/tails!724

Fixes regression introduced with the obfs4proxy 0.0.12 final release:
tails/tails!724 (comment 183582)

I suspect @boyska has the equivalent of 002bd2de
locally but did not push it since the doc does not instruct to do so.

refs tails/sysadmin#17887

Currently translated at 36.8% (14 of 38 strings)

Currently translated at 95.3% (123 of 129 strings)

Currently translated at 16.6% (3 of 18 strings)

Upgrade to Thunderbird 91

Closes #18069

See merge request tails/tails!720

Resolve "Tests for backup are fragile"

Closes #18727

See merge request tails/tails!706

refs #18069

wiki/src/doc/anonymous_internet/tor.ar.po: updating as wiki/src/doc/anonymous_internet/tor.de.po has changed.
wiki/src/doc/anonymous_internet/tor.ca.po: updating as wiki/src/doc/anonymous_internet/tor.de.po has changed.
wiki/src/doc/anonymous_internet/tor.fa.po: updating as wiki/src/doc/anonymous_internet/tor.de.po has changed.
wiki/src/doc/anonymous_internet/tor.id.po: updating as wiki/src/doc/anonymous_internet/tor.de.po has changed.
wiki/src/doc/anonymous_internet/tor.pl.po: updating as wiki/src/doc/anonymous_internet/tor.de.po has changed.
wiki/src/doc/anonymous_internet/tor.sr_Latn.po: updating as wiki/src/doc/anonymous_internet/tor.de.po has changed.
wiki/src/doc/anonymous_internet/tor.tr.po: updating as wiki/src/doc/anonymous_internet/tor.de.po has changed.
wiki/src/doc/anonymous_internet/tor.zh.po: updating as wiki/src/doc/anonymous_internet/tor.de.po has changed.
wiki/src/doc/anonymous_internet/tor.zh_TW.po: updating as wiki/src/doc/anonymous_internet/tor.de.po has changed.