Remove navigation links to /explore when trends are disabled (#19415)

* Remove navigation links to /explore when trends are disabled

* Do not display trends interface when trends are disabled

app/javascript/mastodon/features/getting_started/index.js

@@ -95,7 +95,15 @@ class GettingStarted extends ImmutablePureComponent {
 
     navItems.push(
       <ColumnSubheading key='header-discover' text={intl.formatMessage(messages.discover)} />,
-      <ColumnLink key='explore' icon='hashtag' text={intl.formatMessage(messages.explore)} to='/explore' />,
+    );
+
+    if (showTrends) {
+      navItems.push(
+        <ColumnLink key='explore' icon='hashtag' text={intl.formatMessage(messages.explore)} to='/explore' />,
+      );
+    }
+
+    navItems.push(
       <ColumnLink key='community_timeline' icon='users' text={intl.formatMessage(messages.community_timeline)} to='/public/local' />,
       <ColumnLink key='public_timeline' icon='globe' text={intl.formatMessage(messages.public_timeline)} to='/public' />,
     );