Test suite: allow Thunderbird to connect to test email server even if it's within RFC1918 range

See merge request tails/tails!1268

Help the RM when we FTBFS during release process due to an unused APT source

Closes #20009

See merge request tails/tails!1269

Tor blog post: shift all headings 1 level further

See merge request tails/tails!1270

As Jérôme Charaoui wrote on
https://gitlab.torproject.org/tpo/web/blog/-/merge_requests/235#note_2959499,
"the styling this assumes that for the blog post body, section titles start at
h2, because h1 is used for the blog title".

refs #20009

refs tails/sysadmin#18044

We'll soon need to use this code for 1 Thunderbird scenario too.

We'll soon use it for other things than just Totem.

Closes #19995

Currently translated at 69.6% (23 of 33 strings)

Translation: Tails/wiki/src/news/version_5.16.*.po
Translate-URL: https://translate.tails.boum.org/projects/tails/wikisrcnewsversion_5-16-po/ca/

Currently translated at 72.7% (24 of 33 strings)

Translation: Tails/wiki/src/news/version_5.16.1.*.po
Translate-URL: https://translate.tails.boum.org/projects/tails/wikisrcnewsversion_5-16-1-po/ca/

Currently translated at 64.2% (27 of 42 strings)

Translation: Tails/wiki/src/news/version_5.15.1.*.po
Translate-URL: https://translate.tails.boum.org/projects/tails/wikisrcnewsversion_5-15-1-po/ca/

Currently translated at 58.4% (31 of 53 strings)

Translation: Tails/wiki/src/news/version_5.14.*.po
Translate-URL: https://translate.tails.boum.org/projects/tails/wikisrcnewsversion_5-14-po/ca/

Currently translated at 72.7% (24 of 33 strings)

Translation: Tails/wiki/src/news/version_5.17.*.po
Translate-URL: https://translate.tails.boum.org/projects/tails/wikisrcnewsversion_5-17-po/ca/

Currently translated at 52.9% (27 of 51 strings)

Translation: Tails/wiki/src/news/version_5.12.*.po
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Currently translated at 100.0% (19 of 19 strings)

Translation: Tails/wiki/src/news/gift_of_privacy.*.po
Translate-URL: https://translate.tails.boum.org/projects/tails/wikisrcnewsgift_of_privacy-po/ca/

Currently translated at 100.0% (27 of 27 strings)

Translation: Tails/wiki/src/news/version_5.18.*.po
Translate-URL: https://translate.tails.boum.org/projects/tails/wikisrcnewsversion_5-18-po/ca/

Currently translated at 100.0% (29 of 29 strings)

Translation: Tails/wiki/src/news/version_5.17.1.*.po
Translate-URL: https://translate.tails.boum.org/projects/tails/wikisrcnewsversion_5-17-1-po/ca/

Currently translated at 69.6% (23 of 33 strings)

Translation: Tails/wiki/src/news/version_5.17.*.po
Translate-URL: https://translate.tails.boum.org/projects/tails/wikisrcnewsversion_5-17-po/ca/

Currently translated at 69.6% (23 of 33 strings)

Translation: Tails/wiki/src/news/version_5.16.1.*.po
Translate-URL: https://translate.tails.boum.org/projects/tails/wikisrcnewsversion_5-16-1-po/ca/

Currently translated at 66.6% (22 of 33 strings)

Translation: Tails/wiki/src/news/version_5.16.*.po
Translate-URL: https://translate.tails.boum.org/projects/tails/wikisrcnewsversion_5-16-po/ca/

Currently translated at 100.0% (10 of 10 strings)

Translation: Tails/wiki/src/news/new_domain.*.po
Translate-URL: https://translate.tails.boum.org/projects/tails/wikisrcnewsnew_domain-po/ca/

Currently translated at 61.9% (26 of 42 strings)

Translation: Tails/wiki/src/news/version_5.15.1.*.po
Translate-URL: https://translate.tails.boum.org/projects/tails/wikisrcnewsversion_5-15-1-po/ca/

Currently translated at 12.5% (20 of 159 strings)

Translation: Tails/wiki/src/security/argon2id.*.po
Translate-URL: https://translate.tails.boum.org/projects/tails/wikisrcsecurityargon2id-po/ca/

Currently translated at 100.0% (20 of 20 strings)

Translation: Tails/wiki/src/security/argon2id/cryptsetup_upgrade.inline.*.po
Translate-URL: https://translate.tails.boum.org/projects/tails/wikisrcsecurityargon2idcryptsetup_upgrade-inline-po/ca/

Currently translated at 56.6% (30 of 53 strings)

Translation: Tails/wiki/src/news/version_5.14.*.po
Translate-URL: https://translate.tails.boum.org/projects/tails/wikisrcnewsversion_5-14-po/ca/