test: finish the temp-file cleanup (#14976)

Follow-up to #14785. Routes the tests that still hand-rolled temp paths through
the shared helpers and unifies the temp guards.

- Add ScopedTemporaryDir and a shared ScopedTemporaryPath base under it and
  ScopedTemporaryFile.
- Move test_3mf's round-trip .3mf output out of the TEST_DATA_DIR source tree
  (a fixed-name leak) and test_toolordering's fixed-name temp .gcode (a sharding
  collision) onto ScopedTemporaryFile.
- Move test_config, test_slicing_pipeline_bindings, the test_3mf backup dirs, and
  test_preset_bundle_loading onto the guards.
- Make slic3rutils ScopedDataDir compose ScopedTemporaryDir; dedupe
  test_network_versions' fixture and delete test_plugin_lifecycle's duplicate.

tests/libslic3r/test_config.cpp

@@ -4,6 +4,8 @@
 #include "libslic3r/PrintConfigConstants.hpp"
 #include "libslic3r/LocalesUtils.hpp"
 
+#include "test_utils.hpp"
+
 #include <cereal/types/polymorphic.hpp>
 #include <cereal/types/string.hpp>
 #include <cereal/types/vector.hpp>
@@ -407,8 +409,7 @@ SCENARIO("update_diff_values_to_child_config tolerates legacy machine-limit vect
 // }
 
 TEST_CASE("save_to_json round-trips plugin capability references as strings", "[Config][plugins]") {
-    namespace fs = boost::filesystem;
-    const fs::path tmp = fs::temp_directory_path() / fs::unique_path("orca_plugins_%%%%-%%%%.json");
+    ScopedTemporaryFile tmp(".json");
     const std::vector<std::string> refs = {
         "local_plugin;;inset",
         "cloud_plugin;550e8400-e29b-41d4-a716-446655440000;inset"
@@ -435,8 +436,6 @@ TEST_CASE("save_to_json round-trips plugin capability references as strings", "[
     REQUIRE(reloaded.load_from_json(tmp.string(), substitutions, true, key_values, reason) == 0);
     CHECK(reason.empty());
     CHECK(reloaded.option<ConfigOptionStrings>("slicing_pipeline_plugin")->values == refs);
-
-    fs::remove(tmp);
 }
 
 TEST_CASE("plugin capability references survive string-map serialization", "[Config][plugins]") {