Fix typo in HttpClientHandler.xml (#10410)

Fixed duplicated text

Author: IngweLand

xml/System.Net.Http/HttpClientHandler.xml

@@ -1274,7 +1274,7 @@ handler.ServerCertificateCustomValidationCallback = HttpClientHandler.DangerousA
       <Docs>
         <summary>Gets a value that indicates whether the handler supports automatic response content decompression.</summary>
         <value>
-          <see langword="true" /> if the if the handler supports automatic response content decompression; otherwise <see langword="false" />. The default value is <see langword="true" />.</value>
+          <see langword="true" /> if the handler supports automatic response content decompression; otherwise <see langword="false" />. The default value is <see langword="true" />.</value>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>