bug #18507 [BUG] Delete class 'control-group' in bootstrap 3 (Philippe Degeeter)

This PR was submitted for the 3.0 branch but it was merged into the 2.7 branch instead (closes #18507).

Discussion
----------

[BUG] Delete class 'control-group' in bootstrap 3

| Q             | A
| ------------- | ---
| Branch?       |  3.0
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #18506
| License       | MIT
| Doc PR        | any

Commits
-------

99f61d6 [BUG] Delete class 'control-group' in bootstrap 3

src/Symfony/Bridge/Twig/Resources/views/Form/bootstrap_3_layout.html.twig

@@ -94,14 +94,12 @@
 
 {% block choice_widget_expanded -%}
     {% if '-inline' in label_attr.class|default('') -%}
-        <div class="control-group">
-            {%- for child in form %}
-                {{- form_widget(child, {
-                    parent_label_class: label_attr.class|default(''),
-                    translation_domain: choice_translation_domain,
-                }) -}}
-            {% endfor -%}
-        </div>
+        {%- for child in form %}
+            {{- form_widget(child, {
+                parent_label_class: label_attr.class|default(''),
+                translation_domain: choice_translation_domain,
+            }) -}}
+        {% endfor -%}
     {%- else -%}
         <div {{ block('widget_container_attributes') }}>
             {%- for child in form %}