Fix plugin settings lost on cloud metadata refresh

Cloud catalog records never carry [tool.orcaslicer.plugin.settings], so the
metadata merge wiped the locally-parsed settings and plugins silently ran on
their built-in defaults (ctx.params arrived empty).

tests/slic3rutils/CMakeLists.txt

@@ -5,7 +5,10 @@ add_executable(${_TEST_NAME}_tests
     test_plugin_install.cpp
     test_plugin_lifecycle.cpp
     test_slicing_pipeline_bindings.cpp
+    test_slicing_pipeline_params.cpp
     test_plugin_sort.cpp
+    test_plugin_cloud_metadata.cpp
+    ../fff_print/test_helpers.cpp
     )
 
 if (MSVC)