app: do not sync the PDB context "name" property.

The PDB context name was overwritten when syncing with the parent
context, e.g. the "User" context. Therefore "stale context" warnings,
for instance, were misleadingly telling the "User" context was leaking.

app/pdb/gimppdbcontext.c

@@ -501,6 +501,11 @@ gimp_pdb_context_new (Gimp        *gimp,
    */
   gimp_config_sync (G_OBJECT (parent), G_OBJECT (context), 0);
 
+  /* Reset the proper init name after syncing. */
+  g_object_set (G_OBJECT (context),
+                "name", "PDB Context",
+                NULL);
+
   return GIMP_CONTEXT (context);
 }