use getExe everywhere

nixosModules/constellation-swarm.nix

@@ -91,7 +91,7 @@ in
         set -eu
         umask 077
         for user in ${lib.escapeShellArgs adminUsers}; do
-          ${pkgs.coreutils}/bin/install -m0400 -o "$user" -g root \
+          ${lib.getExe' pkgs.coreutils "install"} -m0400 -o "$user" -g root \
             ${lib.escapeShellArg otelCredential} "$RUNTIME_DIRECTORY/$user"
         done
       '';