Re-enable the tor seccomp sandbox
Due to Tor bug 40317 we had to completely disable the tor seccomp sandbox in !326 (closed) (#17330 (closed)) otherwise the automated test suite fails for essentially all scenarios using tor (see commit message of acad89a4 for details).
So we would ideally revert commit acad89a4 before merging !326 (closed), hopefully by having a
tor with the bug fixed. But if we cannot do that before 4.19 we have to release it any way, and if we cannot fix this before the Sponsor 8 contract ends, we'll just have to explain the situation to them. But I don't think it'll go there... I believe even for me, that barely knows any C and have no experience with seccomp, it would just be a few hours to find a fix -- it's just about allowing a few strings in the sandbox, so the difficulty is just finding where to do that.