Remove UIAccessibilityTraitKeyboardKey to fix touch typing (#52333)

`UIAccessibilityTraitKeyboardKey` was added in #4575 so that `TextInputSemanticsObject` supported VoiceOver gestures for text editing features, such as pinch to select text, and up/down fling to move cursor. After experimenting with it, I found that those features were still available even after removing `UIAccessibilityTraitKeyboardKey`. 

Fixes flutter/flutter#94465.

In Touch Typing Mode:

https://github.com/flutter/engine/assets/15619084/ccfe90ff-d3bc-427b-b1aa-9ec1242c0c89

In Standard Typing Mode:

https://github.com/flutter/engine/assets/15619084/c78b1fb0-0816-41fb-9dd5-ed8b8a4cda2d

[C++, Objective-C, Java style guides]: https://github.com/flutter/engine/blob/main/CONTRIBUTING.md#style

Author: vashworth

shell/platform/darwin/ios/framework/Source/SemanticsObjectTest.mm

@@ -10,6 +10,7 @@
 #import "flutter/shell/platform/darwin/ios/framework/Source/FlutterTouchInterceptingView_Test.h"
 #import "flutter/shell/platform/darwin/ios/framework/Source/SemanticsObject.h"
 #import "flutter/shell/platform/darwin/ios/framework/Source/SemanticsObjectTestMocks.h"
+#import "flutter/shell/platform/darwin/ios/framework/Source/accessibility_text_entry.h"
 
 FLUTTER_ASSERT_ARC
 
@@ -1008,4 +1009,19 @@ - (void)testFlutterPlatformViewSemanticsContainer {
   XCTAssertNil(weakPlatformView);
 }
 
+- (void)testTextInputSemanticsObject {
+  fml::WeakPtrFactory<flutter::AccessibilityBridgeIos> factory(
+      new flutter::testing::MockAccessibilityBridge());
+  fml::WeakPtr<flutter::AccessibilityBridgeIos> bridge = factory.GetWeakPtr();
+
+  flutter::SemanticsNode node;
+  node.label = "foo";
+  node.flags = static_cast<int32_t>(flutter::SemanticsFlags::kIsTextField) |
+               static_cast<int32_t>(flutter::SemanticsFlags::kIsReadOnly);
+  TextInputSemanticsObject* object = [[TextInputSemanticsObject alloc] initWithBridge:bridge uid:0];
+  [object setSemanticsNode:&node];
+  [object accessibilityBridgeDidFinishUpdate];
+  XCTAssertEqual([object accessibilityTraits], UIAccessibilityTraitNone);
+}
+
 @end

shell/platform/darwin/ios/framework/Source/accessibility_text_entry.mm

@@ -304,12 +304,8 @@ - (UIAccessibilityTraits)accessibilityTraits {
   if (![self isAccessibilityBridgeAlive]) {
     return 0;
   }
-  // Adding UIAccessibilityTraitKeyboardKey to the trait list so that iOS treats it like
-  // a keyboard entry control, thus adding support for text editing features, such as
-  // pinch to select text, and up/down fling to move cursor.
-  UIAccessibilityTraits results = [super accessibilityTraits] |
-                                  [self textInputSurrogate].accessibilityTraits |
-                                  UIAccessibilityTraitKeyboardKey;
+  UIAccessibilityTraits results =
+      [super accessibilityTraits] | [self textInputSurrogate].accessibilityTraits;
   // We remove an undocumented flag to get rid of a bug where single-tapping
   // a text input field incorrectly says "empty line".
   // See also: https://github.com/flutter/flutter/issues/52487