Fix DisposeAsync pattern: remove incorrect Dispose(false) call (#50900)

Author: Copilot

docs/standard/garbage-collection/implementing-disposeasync.md

@@ -42,19 +42,13 @@ The `public` parameterless `DisposeAsync()` method is called implicitly in an `a
 public async ValueTask DisposeAsync()
 {
     // Perform async cleanup.
-    await DisposeAsyncCore();
-
-    // Dispose of unmanaged resources.
-    Dispose(false);
+    await DisposeAsyncCore().ConfigureAwait(false);
 
     // Suppress finalization.
     GC.SuppressFinalize(this);
 }
 ```
 
-> [!NOTE]
-> One primary difference in the async dispose pattern compared to the dispose pattern, is that the call from <xref:System.IAsyncDisposable.DisposeAsync> to the `Dispose(bool)` overload method is given `false` as an argument. When implementing the <xref:System.IDisposable.Dispose?displayProperty=nameWithType> method, however, `true` is passed instead. This helps ensure functional equivalence with the synchronous dispose pattern, and further ensures that finalizer code paths still get invoked. In other words, the `DisposeAsyncCore()` method will dispose of managed resources asynchronously, so you don't want to dispose of them synchronously as well. Therefore, call `Dispose(false)` instead of `Dispose(true)`.
-
 ### The `DisposeAsyncCore` method
 
 The `DisposeAsyncCore()` method is intended to perform the asynchronous cleanup of managed resources or for cascading calls to `DisposeAsync()`. It encapsulates the common asynchronous cleanup operations when a subclass inherits a base class that is an implementation of <xref:System.IAsyncDisposable>. The `DisposeAsyncCore()` method is `virtual` so that derived classes can define custom cleanup in their overrides.

docs/standard/garbage-collection/snippets/dispose-async/ExampleConjunctiveDisposable.cs

@@ -13,7 +13,6 @@ public async ValueTask DisposeAsync()
     {
         await DisposeAsyncCore().ConfigureAwait(false);
 
-        Dispose(disposing: false);
         GC.SuppressFinalize(this);
     }