Revert "Re-merge Switch web-render option default to auto. Add documentation (#23187)" (#23246)

This reverts commit 08d5c33b02996e3384f48f9160ed2047b5be4c66.
diff --git a/lib/web_ui/dev/README.md b/lib/web_ui/dev/README.md
index ef6d098..309ca9a 100644
--- a/lib/web_ui/dev/README.md
+++ b/lib/web_ui/dev/README.md
@@ -49,8 +49,6 @@
 felt test --unit-tests-only
 ```
 
-Most of the unit tests are run using the html rendering backends. The unit tests under `test/cancaskit` directory use `canvaskit` backend.
-
 To run integration tests only. For now these tests are only available on Chrome Desktop browsers. These tests will fetch the flutter repository for using `flutter drive` and `flutter pub get` commands. The repository will be synced to the youngest commit older than the engine commit.
 
 ```
@@ -63,12 +61,6 @@
 felt test --integration-tests-only --use-system-flutter
 ```
 
-We can use different rendering backends for running the integrations tests. If one wants to use html backend use the following command. `web-renderer` flag accepts 3 different options: `html`, `canvaskit`, `auto`.
-
-```
-felt test --integration-tests-only --web-renderer=html
-```
-
 To run tests on Firefox (this will work only on a Linux device):
 
 ```
diff --git a/lib/web_ui/dev/test_runner.dart b/lib/web_ui/dev/test_runner.dart
index a9e9397..9a67335 100644
--- a/lib/web_ui/dev/test_runner.dart
+++ b/lib/web_ui/dev/test_runner.dart
@@ -619,8 +619,6 @@
       '--enable-experiment=non-nullable',
       '--no-sound-null-safety',
       if (input.forCanvasKit) '-DFLUTTER_WEB_USE_SKIA=true',
-      if (!input.forCanvasKit) '-DFLUTTER_WEB_AUTO_DETECT=false',
-      if (!input.forCanvasKit) '-DFLUTTER_WEB_USE_SKIA=false',
       '-O2',
       '-o',
       targetFileName, // target path.
diff --git a/lib/web_ui/lib/src/engine/canvaskit/initialization.dart b/lib/web_ui/lib/src/engine/canvaskit/initialization.dart
index 61fe5fe..20a9ecd 100644
--- a/lib/web_ui/lib/src/engine/canvaskit/initialization.dart
+++ b/lib/web_ui/lib/src/engine/canvaskit/initialization.dart
@@ -31,7 +31,7 @@
 /// Using flutter tools option "--web-render=auto" would set the value to true.
 /// Otherwise, it would be false.
 const bool _autoDetect =
-    bool.fromEnvironment('FLUTTER_WEB_AUTO_DETECT', defaultValue: true);
+    bool.fromEnvironment('FLUTTER_WEB_AUTO_DETECT', defaultValue: false);
 
 /// Enable the Skia-based rendering backend.
 ///