Revert "[web] Reland: Enable the new rich paragraph implementation (#23659)"

This reverts commit d7b25f9a.

lib/web_ui/lib/src/engine/web_experiments.dart

@@ -45,7 +45,7 @@ class WebExperiments {
 
   static const bool _defaultUseCanvasRichText = const bool.fromEnvironment(
     'FLUTTER_WEB_USE_EXPERIMENTAL_CANVAS_RICH_TEXT',
-    defaultValue: true,
+    defaultValue: false,
   );
 
   bool _useCanvasRichText = _defaultUseCanvasRichText;

lib/web_ui/test/engine/web_experiments_test.dart

@@ -11,7 +11,7 @@ import 'package:test/test.dart';
 import 'package:ui/src/engine.dart';
 
 const bool _defaultUseCanvasText = true;
-const bool _defaultUseCanvasRichText = true;
+const bool _defaultUseCanvasRichText = false;
 
 void main() {
   internalBootstrapBrowserTest(() => testMain);

lib/web_ui/test/golden_tests/engine/canvas_golden_test.dart

@@ -230,7 +230,7 @@ void testMain() async {
     canvas.drawParagraph(paragraph, const Offset(180, 50));
 
     expect(
-      canvas.rootElement.querySelectorAll('p').map<String>((e) => e.text).toList(),
+      canvas.rootElement.querySelectorAll('p').map<String>((e) => e.innerText).toList(),
       <String>[text],
       reason: 'Expected to render text using HTML',
     );