librsvg: remove installed tests

Build will start failing with the following error in 2.55.1 due to `/build/librsvg-2.55.1/.libs` ending up in rpath:

    RPATH of binary /nix/store/78k70limslvxs6y98hdirbcixl3car1q-librsvg-2.55.1-installedTests/libexec/installed-tests/RSVG/api contains a forbidden reference to /build/

nixos/tests/installed-tests/default.nix

@@ -101,7 +101,6 @@ in
   json-glib = callInstalledTest ./json-glib.nix {};
   ibus = callInstalledTest ./ibus.nix {};
   libgdata = callInstalledTest ./libgdata.nix {};
-  librsvg = callInstalledTest ./librsvg.nix {};
   glib-testing = callInstalledTest ./glib-testing.nix {};
   libjcat = callInstalledTest ./libjcat.nix {};
   libxmlb = callInstalledTest ./libxmlb.nix {};

nixos/tests/installed-tests/librsvg.nix

@@ -1,9 +0,0 @@
-{ pkgs, makeInstalledTest, ... }:
-
-makeInstalledTest {
-  tested = pkgs.librsvg;
-
-  testConfig = {
-    virtualisation.memorySize = 2047;
-  };
-}

pkgs/development/libraries/librsvg/default.nix

@@ -22,7 +22,6 @@
 , vala
 , withIntrospection ? stdenv.hostPlatform == stdenv.buildPlatform
 , gobject-introspection
-, nixosTests
 , _experimental-update-script-combinators
 , common-updater-scripts
 , jq
@@ -33,7 +32,7 @@ stdenv.mkDerivation rec {
   pname = "librsvg";
   version = "2.55.0";
 
-  outputs = [ "out" "dev" "installedTests" ] ++ lib.optionals withIntrospection [
+  outputs = [ "out" "dev" ] ++ lib.optionals withIntrospection [
     "devdoc"
   ];
 
@@ -93,16 +92,10 @@ stdenv.mkDerivation rec {
     # https://github.com/NixOS/nixpkgs/pull/117081#issuecomment-827782004
     (lib.enableFeature (withIntrospection && !stdenv.isDarwin) "vala")
 
-    "--enable-installed-tests"
     "--enable-always-build-tests"
   ] ++ lib.optional stdenv.isDarwin "--disable-Bsymbolic"
     ++ lib.optional (stdenv.buildPlatform != stdenv.hostPlatform) "RUST_TARGET=${rust.toRustTarget stdenv.hostPlatform}";
 
-  makeFlags = [
-    "installed_test_metadir=${placeholder "installedTests"}/share/installed-tests/RSVG"
-    "installed_testdir=${placeholder "installedTests"}/libexec/installed-tests/RSVG"
-  ];
-
   doCheck = false; # all tests fail on libtool-generated rsvg-convert not being able to find coreutils
 
   # It wants to add loaders and update the loaders.cache in gdk-pixbuf
@@ -176,10 +169,6 @@ stdenv.mkDerivation rec {
         updateSource
         updateLockfile
       ];
-
-    tests = {
-      installedTests = nixosTests.installed-tests.librsvg;
-    };
   };
 
   meta = with lib; {