templates: Clean various items off HTML linter bad list.

Most of these already pass the linter; for the ones that don't, the
fixes are small and don't make the HTML any worse.

templates/zerver/apps.html

@@ -3,9 +3,7 @@
 {% block customhead %}
 <meta name="viewport" content="width=device-width, initial-scale=1.0">
 <style media="screen">
-    .app.portico-page {
-        padding-bottom: 0px;
-    }
+    .app.portico-page { padding-bottom: 0px; }
 </style>
 {% stylesheet 'portico' %}
 {% stylesheet 'landing-page' %}

templates/zerver/hello.html

@@ -574,7 +574,8 @@
                     the world to stay involved, even years after their
                     batches finish. No other tool has a user
                     experience that scales to a community of our
-                    size.</blockquote>
+                    size.
+                </blockquote>
                 <cite>Nick Bergson-Shilcock, founder and CEO, Recurse Center</cite>
             </div>
 

tools/check-templates

@@ -94,18 +94,13 @@ def check_html_templates(templates, all_dups):
         # and might eventually require more scrutiny for things like
         # localization.  See github #1236.
         bad_files = [
-            'static/html/5xx.html',
             'templates/corporate/zephyr-mirror.html',
             'templates/zerver/api.html',
             'templates/zerver/api_endpoints.html',
-            'templates/zerver/apps.html',
             'templates/zerver/features.html',
-            'templates/zerver/hello.html',
             'templates/zerver/home.html',
-            'templates/zerver/integrations/index.html',
             'templates/zerver/login.html',
             'templates/zerver/markdown_help.html',
-            'templates/zerver/register.html',
             'templates/zerver/search_operators.html',
             'zerver/webhooks/taiga/doc.html',
             'zerver/webhooks/zendesk/doc.html',
@@ -119,7 +114,6 @@ def check_html_templates(templates, all_dups):
         'templates/analytics/stats.html',
         'templates/corporate/zephyr-mirror.html',
         'templates/zerver/api.html',
-        'templates/zerver/apps.html',
         'templates/zerver/compose.html',
         'templates/zerver/hello.html',
         'templates/zerver/home.html',