plugins: remove laplace/sobel from menu

The generic edge detect plug-in convers both _and_ is more configurable.
For GEGL it _might_ make sense to internally have laplace/sobel, though
it is not important to have it visible in a end user/photographer menu.

plug-ins/common/edge-laplace.c

@@ -87,8 +87,6 @@ query (void)
                           GIMP_PLUGIN,
                           G_N_ELEMENTS (args), 0,
                           args, NULL);
-
-  gimp_plugin_menu_register (PLUG_IN_PROC, "<Image>/Filters/Edge-Detect");
 }
 
 static void

plug-ins/common/edge-sobel.c

@@ -123,8 +123,6 @@ query (void)
                           GIMP_PLUGIN,
                           G_N_ELEMENTS (args), 0,
                           args, NULL);
-
-  gimp_plugin_menu_register (PLUG_IN_PROC, "<Image>/Filters/Edge-Detect");
 }
 
 static void