Merge branch '5.3' into 5.4

* 5.3:
  [Tests] Remove some unused fixtures
  added missing translations for portuguese [#43726]
  [HttpClient][Mime] Add correct IDN flags for IDNA2008 compliance
  properly parse quoted strings tagged with !!str
  do not merge label classes into expanded choice labels
  [Serializer] PropertyNormalizer - return unique (i.e. filter duplicate ) attributes in extractAttributes function

Author: derrabus

Resources/views/Form/bootstrap_3_layout.html.twig

@@ -90,9 +90,6 @@
         {%- if required -%}
             {%- set label_attr = label_attr|merge({class: (label_attr.class|default('') ~ ' required')|trim}) -%}
         {%- endif -%}
-        {%- if parent_label_class is defined -%}
-            {%- set label_attr = label_attr|merge({class: (label_attr.class|default('') ~ ' ' ~ parent_label_class)|trim}) -%}
-        {%- endif -%}
         {%- if label is not same as(false) and label is empty -%}
             {%- if label_format is not empty -%}
                 {%- set label = label_format|replace({

Resources/views/Form/bootstrap_4_layout.html.twig

@@ -283,9 +283,6 @@
         {%- if required -%}
             {%- set label_attr = label_attr|merge({class: (label_attr.class|default('') ~ ' required')|trim}) -%}
         {%- endif -%}
-        {%- if parent_label_class is defined -%}
-            {%- set label_attr = label_attr|merge({class: (label_attr.class|default('') ~ ' ' ~ parent_label_class)|replace({'checkbox-inline': '', 'radio-inline': '', 'checkbox-custom': '', 'radio-custom': ''})|trim}) -%}
-        {%- endif -%}
         {%- if label is not same as(false) and label is empty -%}
             {%- if label_format is not empty -%}
                 {%- set label = label_format|replace({

Resources/views/Form/foundation_5_layout.html.twig

@@ -253,9 +253,6 @@
     {% if errors|length > 0 -%}
         {% set label_attr = label_attr|merge({class: (label_attr.class|default('') ~ ' error')|trim}) %}
     {% endif %}
-    {% if parent_label_class is defined %}
-        {% set label_attr = label_attr|merge({class: (label_attr.class|default('') ~ parent_label_class)|trim}) %}
-    {% endif %}
     {% if label is empty %}
         {%- if label_format is not empty -%}
             {% set label = label_format|replace({