Remove obsolete disabling of nf_conntrack_helper

Closes #19557

See merge request tails/tails!1109

Closes #19585

This step depends on the included offline copy of our doc:

    I successfully start the Unsafe Browser in "<lang_code>"

Test suite: allow the pattern to cover slightly less of the write cache

Closes #19583

See merge request tails/tails!1098

Additional Software: Use valid D-Bus name as app name

Closes #19584

See merge request tails/tails!1099

This parameter is not supported anymore, and what it did is obsolete (there's
no such helpers anymore):
https://github.com/torvalds/linux/commit/b118509076b39cc5e616c0680312b5caaca535fe

refs #19557

Test suite: Try to catch another case of "Display output is not active"

Closes #18953

See merge request tails/tails!1106

On #19583 we reviewed test results on Jenkins and found cases where even
less of the write cache was covered by the pattern. The lowest was 86%.
We decided to allow those tests to pass to have fewer irrelevant test
failures on Jenkins.

Similar to d6710dde, we've seen this
scenario fail sometimes when it covered only 92.5%.

Closes #19583.

tps: Fix "python.UnknownError" returned for builtin errors

Closes #19578

See merge request tails/tails!1095

Test suite: Fix Electrum test

Closes #19589

See merge request tails/tails!1105

Closes #19589

A valid D-Bus name must not contain any "-".

This was causing issues since commit
9d7d7e49 made
tails-additional-software-config a D-Bus activatable app.

Closes #19584

Don't allow amnesia outside of the Unsafe Browser sandbox to write to
directories below /var/lib/unsafe-browser/chroot, which contain the
Unsafe Browser config.

Closes #19585

Test suite: Press escape to wake up the display

Closes #18953

See merge request tails/tails!1089

Test suite: Fix step "persistent Greeter options were restored"

Closes #19558

See merge request tails/tails!1084

Welcome Screen: Support login kernel command-line option

See merge request tails/tails!1093

We don't have to reboot after creating a Persistent Storage anymore.

I saw this fail because the button was not sensitive yet but it was a
split second later.

The step was failing on my system because a few pixels are missing on
the bottom of the screen keyboard.

Closes #19558

We used to just call `gettext` in the VM, which uses the current system
language. Now we always translate to the language specified in
$language, which allows us to also translate strings to the language
configured in the greeter.

Note that this required changing the lang_code of chinese from zh to
zh_CN because otherwise `gettext` wouldn't translate it. This should not
cause anything to break because it apparently for Chinese, the lang_code
isn't used anywhere else currently.

We need this to set the LANGUAGE environment variable to make gettext
translate a string to another language than the one currently set on the
system (that's needed in the greeter, where language changes in the
greeter don't propagate to the system until the greeter is closed).

It sometimes happens on my local system that chutney doesn't start at
all and I have to delete /tmp/TailsToaster/chutney-data/ to fix that.
Currently I only notice that that's the case after the start time of 10
minutes has passed. Chutney never takes that long to start on my system,
so I want to reduce that startup time for my local runs.

This option is a convenience feature for developers. It makes the
greeter automatically log in with the default settings.

Fix race when starting tails-ibus-proxy.service

See merge request tails/tails!1086

tps: Fix activation of feature in inconsistent state

Closes #19368, #19331, #8447, #19291, and #19376

See merge request tails/tails!1010

Resolve "myspace.com has become incompatible with our htpdate setup"

Closes #19561

See merge request tails/tails!1085

Minor fixes

See merge request tails/tails!1094

This script modifies the system config in depth.

It seems like the module which contains builtin errors was renamed from
"__builtin__" to "builtins" in Python 3.9.

Also try to make the warning that's printed when the error name can't be
used as a D-Bus error name more clear.

Pressing escape repeatedly did not fix #18953 yet, but the snapshots
for which the error occurred were restored successfully multiple times
in other tests from the same test run, which makes it likely that
trying again to restore it could succeed.

In the cases where restoring the snapshot succeeded, the display was
activated within one second, so we reduce the time we try to wake up the
display to 10 seconds.

Closes #18953

Additional Software: Fix launched apps not accessible via Dogtail

Closes #19131, #17365, and #19233

See merge request !1092

Other fixes included in this commit:

- Give the display a bit more time to wake up (40s instead of 20s)
- Also wait for display when restoring greeter snapshots

Avoids these messages being printed in the journal:

    systemd-udevd[563]: /etc/udev/rules.d/70-protect-boot-medium-for-udisks.rules:9 ENV key takes '==', '!=', '=', or '+=' operator, assuming '=', but please fix it.
    systemd-udevd[563]: /etc/udev/rules.d/70-protect-boot-medium-for-udisks.rules:16 ENV key takes '==', '!=', '=', or '+=' operator, assuming '=', but please fix it.