openssh: put tests into passthru

openssh tests are very slow (they take ~30 mins because they are not
parallelized). This makes rebuilding (esp. after changes e.g. to
systemd) painful. Putting the tests into a separate derivation solves
this without losing any testing capability.

Debian does the same: https://packages.debian.org/sid/openssh-tests

pkgs/tools/networking/openssh/common.nix

@@ -28,6 +28,7 @@
 , libfido2
 , hostname
 , nixosTests
+, openssh # This is needed to override itself in passthru.tests
 , withFIDO ? stdenv.hostPlatform.isUnix && !stdenv.hostPlatform.isMusl
 , withPAM ? stdenv.hostPlatform.isLinux
 , linkOpenssl ? true
@@ -100,7 +101,7 @@ stdenv.mkDerivation {
 
  hardeningEnable = [ "pie" ];
 
- doCheck = true;
+ doCheck = false;
  enableParallelChecking = false;
  nativeCheckInputs = [ openssl ] ++ lib.optional (!stdenv.isDarwin) hostname;
  preCheck = lib.optionalString (stdenv.hostPlatform == stdenv.buildPlatform) ''
@@ -167,6 +168,9 @@ stdenv.mkDerivation {
  ];
 
  passthru.tests = {
+ openssh = openssh.overrideAttrs (_: {
+ doCheck = true;
+ });
  borgbackup-integration = nixosTests.borgbackup;
  };