nixos/gns3-server: fix ubridge_path

[dani0854]

Description of changes

Ubridge doesn't work since the path passed to gns3-server is to the nix store version rather than security wrapper created just before. This PR fixes this

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandboxing enabled in nix.conf? (See Nix manual)
  • sandbox = relaxed
  • sandbox = true
• Tested, as applicable:
  • NixOS test(s) (look inside nixos/tests)
  • and/or package tests
  • or, for functions and "core" functionality, tests in lib/tests or pkgs/test
  • made sure NixOS tests are linked to the relevant packages
• Tested compilation of all packages that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review rev HEAD". Note: all changes have to be committed, also see nixpkgs-review usage
• Tested basic functionality of all binary files (usually in ./result/bin/)
• 24.05 Release Notes (or backporting 23.05 and 23.11 Release notes)
  • (Package updates) Added a release notes entry if the change is major or breaking
  • (Module updates) Added a release notes entry if the change is significant
  • (Module addition) Added a release notes entry if adding a new NixOS module
• Fits CONTRIBUTING.md.

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[dani0854]

Now I get:

Could not determine uBridge version for /run/wrappers/bin/ubridge

I guess it has something to do with permissions. But since there is no logging in the gns3server for this part, I would probably need to patch the gns3-server package to get that message.

I have tried adding o=rx to security wrapper, but that didn't fix the problem. And since it runs fine when launched as normal user with docker and ubridge groups, I suspect it has something to do with systemd service config.

[dani0854]

Created an issue for further discussion #292258

[dani0854]

Closing in favour of #303442