Investigate which of our custom packages are still relevant for Bullseye

Tick off package once its decision has been implemented in the feature-bullseye APT suite:

• desktop-file-utils: comes from #17023 (closed); the patch lamby wrote for us was upstreamed in 0.24, which is in Bullseye but wasn't in Buster, so it is expected that we should be able to drop this patch. Indeed, diffoscope didn't report anything related to this. So let's drop it!
• fontconfig: comes from #15187 (closed); more context on https://bugs.debian.org/864082; the patch has not been applied upstream so we need a custom package.
• VeraCrypt patched packages: Drop? In theory all patches were upstreamed, and while some functionality are not enabled by default, we enable it at runtime (/etc/udisks2/tcrypt.conf)
  • gjs
  • gnome-shell
  • gtk+3.0
  • gvfs
• ibus: #16291 (closed), https://salsa.debian.org/tails-team/ibus/commits/tails/buster; unfortunately the problem is back, so we need a patched package.
• live-boot: Keep as-is.
• network-manager: Will need an updated package to deal with #16948 (closed)
• onioncircuits: Let's drop our old package and install 0.7-2 from Bullseye! It works fine, and looking at the diff it seems that 0.7-2 only improves things.

diffoscope-feature_bullseye_bf08ca7f4f+devel_a5a025e2e5.html

Once all this has been sorted out:

• Revert dfed1fb3 and adjust the corresponding checks