See: https://bugzilla.mozilla.org/show_bug.cgi?id=1648555 for the
upstream bug.

I missed them on the server-side.

Updating glean_parser to 1.28.6 fixes the remaining part of #40086 as
well.

This compiles and links NSS/application-services with lto, and also adds a check
which will make the building of the application-services project fail if it finds
networking symbols in the final built libraries.

We take the shortcut and just overwrite all the geckoview .aar files in
our gradle-dependencies that are not breaking the build, which helps
with fenix#40017, too.

In addition, we delete the hard-coded Fenix specific `version` and we
use `abbrev`, instead.

We need to make sure we just set MOZ_BUILD_DATE and adapt the format
where it is actually needed. See: fenix#40059 for the Fenix part that
makes use of that to fix #40084.

We bump Fenix to 81.1.1 and android-components to 57.0.6 while GeckoView
is staying on 81.0b9 to save us another round of rebasing.

It turns out that declaring a `beta_version` and including that in the
version number for a branch name might not have been the best idea given
that not all our branches are based on mozilla-beta. So, we drop that
and add the beta version directly when needed.

We sort now in a way that makes the output reproducible on different
machines and exclude .module files, too, as we do not need them.

Versions bump and Changelog update

Additionally, we clean up our projects removing Linux workarounds not
needed under Jessie anymore.

CentOS 6 will be EOL later this year (Nov 2020). We are removing support
for it beginning with 10.5 which will get released around mid-2021.

Apparently we can't just replace the torbrowser-android-* targets with
android-* ones when including the Rust compilers for application-services.
Thus, we revert that part of the patch for #40070. See: #40094 for more
details.