Do not call callLoadPlugins() every time a SCRIPTING_TOOL is created.

(i.e. from board editor and from fp editor)
Once is enough.
Once plugins are loaded, calling LoadPlugins() from fpeditor disable plugins
in board editor
Fixes #9846
https://gitlab.com/kicad/code/kicad/issues/9846

pcbnew/python/scripting/pcb_scripting_tool.cpp

@@ -67,9 +67,9 @@ bool SCRIPTING_TOOL::Init()
         PyObject* sys_mod = PyImport_GetModuleDict();
         PyDict_SetItemString( sys_mod, "_pcbnew", mod );
         Py_DECREF( mod );
-    }
 
-    callLoadPlugins();
+        callLoadPlugins();
+    }
 
     return true;
 }