pulseaudio: fix evaluation with Nix 2.3

[sternenseemann]

Path interpolation syntax has been introduced in Nix 2.4 and may not be
used in nixpkgs which needs to be able to be evaluated with Nix 2.3.

cc fyi @wegank

Description of changes

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandbox = true set in nix.conf? (See Nix manual)
• 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/)
• 22.11 Release Notes (or backporting 22.05 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
  • (Release notes changes) Ran nixos/doc/manual/md-to-db.sh to update generated release notes
• Fits CONTRIBUTING.md.

[wegank]

Oh I actually opened #188275 for this. I guess that PR can be closed now.

[sternenseemann]

If it's still dead code, I guess it could be removed regardless, I don't know.

[ncfavier]

BTW, why are we still supporting Nix 2.3? The 22.05 channel has 2.8...

[wegank]

Probably #204371 (comment) . Also FreshPorts' Nix is on 2.3.