Remove disable_indented_code_blocks (#4988) [deploy]

We have decided enable indented-code-block because it is an expected
markdown feature. The trade-off here is that backticks will cause
rendering issues in codeblock.

config/initializers/redcarpet.rb

@@ -2,7 +2,6 @@
   autolink: true,
   no_intra_emphasis: true,
   fenced_code_blocks: true,
-  disable_indented_code_blocks: true,
   lax_html_blocks: true,
   lax_spacing: true,
   strikethrough: true,

spec/support/fixtures/approvals/user_preview_article_body.approved.html

@@ -107,6 +107,12 @@ the present is our past.</p>
 
 
 
+<div class="highlight"><pre class="highlight plaintext"><code>// indented codeblock should work
+function hello() {
+  console.log("hello");
+}
+</code></pre></div>
+
 <ul><li>[x] @mentions, #refs, <a href="">links</a>, <strong>formatting</strong>, and <del>tags</del> supported</li>
 <li>[x] list syntax required (any unordered or ordered list supported)</li>
 <li>[x] this is a complete item</li>

spec/support/fixtures/sample_article_template_spec.txt

@@ -61,6 +61,11 @@ function fancyAlert(arg) {
 }
 ```
 
+    // indented codeblock should work
+    function hello() {
+      console.log("hello");
+    }
+
 
 - [x] @mentions, #refs, [links](), **formatting**, and <del>tags</del> supported
 - [x] list syntax required (any unordered or ordered list supported)