Canvas text: fix clearing existing style

Fixes T5187.
This fixes a leak in evas_textblock_style_user_pop, that made use of the
new key-based efl_canvas_text_style_set api.

@fix

src/lib/evas/canvas/evas_object_textblock.c

@@ -6928,6 +6928,7 @@ _efl_canvas_text_style_set(Eo *eo_obj, Efl_Canvas_Text_Data *o, const char *key,
         else
           {
              o->styles = eina_list_remove(o->styles, ts);
+             ts->objects = eina_list_remove(ts->objects, eo_obj);
              evas_textblock_style_free(ts);
           }