[commands] Undeprecate deferredProxy (#7417)

This changes the way deferred proxy is implemented to not use the
deprecated ProxyCommand constructor.

This function serves a good purpose that should be kept IMO. The
constructor was confusing but this is just good syntactic sugar over
`defer(() -> supplier.get().asProxy())`.

Signed-off-by: Jade Turner <spacey-sooty@proton.me>

wpilibNewCommands/src/main/java/edu/wpi/first/wpilibj2/command/Commands.java

@@ -198,15 +198,11 @@ public final class Commands {
    *
    * @param supplier the command supplier
    * @return the command
-   * @deprecated The ProxyCommand supplier constructor has been deprecated in favor of directly
-   *     proxying a {@link DeferredCommand}, see ProxyCommand documentation for more details. As a
-   *     replacement, consider using `defer(supplier).asProxy()`.
    * @see ProxyCommand
+   * @see DeferredCommand
    */
-  @Deprecated(since = "2025", forRemoval = true)
-  @SuppressWarnings("removal")
   public static Command deferredProxy(Supplier<Command> supplier) {
-    return new ProxyCommand(supplier);
+    return defer(() -> supplier.get().asProxy(), Set.of());
   }
 
   // Command Groups