Fix style-lint errors in wiki.scss

There were two errors: duplicate styles and @extend used with a class
name. I added `.top-area` class to all the instances where
`.wiki-page-header` is used since %top-area didn't really make a lot of
sense as a placeholder selector. This is also consistent with behaviour
on other pages where the `.top-area` class is used alongside the other
classes for the specific header styling.

app/assets/stylesheets/pages/wiki.scss

-.new-wiki-page {
-  .new-wiki-page-slug-tip {
-    display: inline-block;
-    max-width: 100%;
-    margin-top: 5px;
-  }
-}
-
-.wiki-form {
-  .edit-wiki-page-slug-tip {
-    display: inline-block;
-    max-width: 100%;
-    margin-top: 5px;
-  }
-}
-
 .title .edit-wiki-header {
   width: 780px;
   margin-left: auto;
@@ -22,7 +6,6 @@
 }
 .wiki-page-header {
-  @extend .top-area;
   position: relative;
   .wiki-breadcrumb {

app/views/projects/wikis/_form.html.haml

@@ -14,7 +14,7 @@
     .col-sm-12
       = f.text_field :title, class: 'form-control qa-wiki-title-textbox', value: @page.title
       - if @page.persisted?
-        %span.edit-wiki-page-slug-tip
+        %span.d-inline-block.mw-100.prepend-top-5
           = icon('lightbulb-o')
           = s_("WikiEditPageTip|Tip: You can move this page by adding the path to the beginning of the title.")
           = link_to icon('question-circle'), help_page_path('user/project/wiki/index', anchor: 'moving-a-wiki-page'), target: '_blank'

app/views/projects/wikis/_new.html.haml

@@ -11,7 +11,7 @@
             = label_tag :new_wiki_path do
               %span= s_("WikiPage|Page slug")
             = text_field_tag :new_wiki_path, nil, placeholder: s_("WikiNewPagePlaceholder|how-to-setup"), class: 'form-control', required: true, :'data-wikis-path' => project_wikis_path(@project), autofocus: true
-            %span.new-wiki-page-slug-tip
+            %span.d-inline-block.mw-100.prepend-top-5
               = icon('lightbulb-o')
               = s_("WikiNewPageTip|Tip: You can specify the full path for the new file. We will automatically create any missing directories.")
           .form-actions

app/views/projects/wikis/edit.html.haml

@@ -5,7 +5,7 @@
 = wiki_page_errors(@error)
-.wiki-page-header.has-sidebar-toggle
+.wiki-page-header.top-area.has-sidebar-toggle
   %button.btn.btn-default.sidebar-toggle.js-sidebar-wiki-toggle{ role: "button", type: "button" }
     = icon('angle-double-left')

app/views/projects/wikis/git_access.html.haml

 - @content_class = "limit-container-width" unless fluid_layout
 - page_title s_("WikiClone|Git Access"), _("Wiki")
-.wiki-page-header.has-sidebar-toggle
+.wiki-page-header.top-area.has-sidebar-toggle
   %button.btn.btn-default.d-block.d-sm-block.d-md-none.float-right.sidebar-toggle.js-sidebar-wiki-toggle{ role: "button", type: "button" }
     = icon('angle-double-left')

app/views/projects/wikis/history.html.haml

 - page_title _("History"), @page.human_title, _("Wiki")
-.wiki-page-header.has-sidebar-toggle
+.wiki-page-header.top-area.has-sidebar-toggle
   %button.btn.btn-default.sidebar-toggle.js-sidebar-wiki-toggle{ role: "button", type: "button" }
     = icon('angle-double-left')

app/views/projects/wikis/pages.html.haml

@@ -5,7 +5,7 @@
 - sort_title = wiki_sort_title(params[:sort])
 %div{ class: container_class }
-  .wiki-page-header
+  .wiki-page-header.top-area
     .nav-text.flex-fill
       %h2.wiki-page-title

app/views/projects/wikis/show.html.haml

@@ -4,7 +4,7 @@
 - page_title @page.human_title, _("Wiki")
 - add_to_breadcrumbs _("Wiki"), project_wiki_path(@project, :home)
-.wiki-page-header.has-sidebar-toggle
+.wiki-page-header.top-area.has-sidebar-toggle
   %button.btn.btn-default.sidebar-toggle.js-sidebar-wiki-toggle{ role: "button", type: "button" }
     = icon('angle-double-left')

changelogs/unreleased/59829-fix-style-lint-wiki.yml

+---
+title: Fix the style-lint errors and warnings for `app/assets/stylesheets/pages/wiki.scss`
+merge_request: 31656
+author:
+type: other