Remove placeholder in SDG related list

Its value is difficult to read due to the low contrast between the color
of the field and the color of the placeholder text, and we already have
the same information in the hint above it.

app/assets/javascripts/sdg/related_list_selector.js

@@ -89,6 +89,12 @@
       suggestions_input[0].id = original_input[0].id + "_suggestions";
 
       $("[for='" + original_input[0].id + "']").attr("for", suggestions_input[0].id);
+
+      suggestions_input.attr("aria-describedby", original_input.attr("aria-describedby"));
+
+      if ($(original_input).attr("placeholder") === undefined) {
+        suggestions_input.removeAttr("placeholder");
+      }
     }
   };
 }).call(this);

app/components/sdg/related_list_selector_component.html.erb

@@ -13,7 +13,6 @@
 
     <%= f.text_field :related_sdg_list,
                       class: "input",
-                      placeholder: t("sdg.related_list_selector.placeholder"),
                       hint: sanitize(t("sdg.related_list_selector.hint",
                                       link: link_to(t("sdg.related_list_selector.help.text"),
                                                       sdg_help_path,

config/locales/en/sdg.yml

@@ -632,7 +632,6 @@ en:
         title: "Which SDGs and targets are aligned with my %{record}?"
         text: "SDG help page"
       hint: You can introduce the code of a specific goal/target or a text to find one. For more information visit the %{link}.
-      placeholder: "Write a goal or target code or description"
       remove_tag: "Remove"
       title: "Sustainable Development Goals and Targets"
     targets:

config/locales/es/sdg.yml

@@ -632,7 +632,6 @@ es:
         title: "¿Qué ODS y metas se alinean con mi %{record}?"
         text: "página de ayuda de ODS"
       hint: Puedes introducir el código de un objetivo/meta específico o un texto para encontrar uno. Para más información visita la %{link}.
-      placeholder: "Escribe las etiquetas que desees"
       remove_tag: "Eliminar"
       title: "Objetivos de Desarrollo Sostenible y Metas"
     targets: