remove custom markdown rendering (#24538)

* remove custom markdown rendering

* remove from release
old-commit-hash: 222c7cd60d

common/tests/test_markdown.py

@@ -1,26 +0,0 @@
-#!/usr/bin/env python3
-from markdown_it import MarkdownIt
-import os
-import unittest
-
-from common.basedir import BASEDIR
-from common.markdown import parse_markdown
-
-
-class TestMarkdown(unittest.TestCase):
-  # validate that our simple markdown parser produces the same output as `markdown_it` from pip
-  def test_current_release_notes(self):
-    self.maxDiff = None
-
-    with open(os.path.join(BASEDIR, "RELEASES.md")) as f:
-      for r in f.read().split("\n\n"):
-
-        # No hyperlink support is ok
-        if '[' in r:
-          continue
-
-        self.assertEqual(MarkdownIt().render(r), parse_markdown(r))
-
-
-if __name__ == "__main__":
-  unittest.main()