fix remarks CDATA format in sql apis (#4298)

Author: TianqiZhang

xml/System.Data.SqlClient/SqlTransaction.xml

@@ -301,11 +301,7 @@
         <summary>Releases the unmanaged resources used and optionally releases the managed resources.</summary>
         <remarks>
           <format type="text/markdown"><![CDATA[
-
-<format type="text/markdown">   
- ## Remarks   This method calls <xref:System.Data.Common.DbTransaction.Dispose%2A>.
- </format>
-
+  This method calls <xref:System.Data.Common.DbTransaction.Dispose%2A>.
           ]]></format>
         </remarks>
       </Docs>

xml/System.Data.SqlTypes/SqlFileStream.xml

@@ -441,10 +441,7 @@
         <summary>Releases the unmanaged resources used and optionally releases the managed resources.</summary>
         <remarks>
           <format type="text/markdown"><![CDATA[
-
-<format type="text/markdown">   ## Remarks   This method calls <xref:Stream.Dispose%2A>.
- </format>
-
+This method calls <xref:Stream.Dispose%2A>.
           ]]></format>
         </remarks>
       </Docs>

xml/System.Net.Http/SocketsHttpHandler.xml

@@ -363,13 +363,11 @@ Draining occurs when a request is cancelled or a response is disposed prior to f
         <summary>Gets or sets the maximum length, in kilobytes (1024 bytes), of the response headers.</summary>
         <value>The maximum size of the header portion from the server response, in kilobytes.</value>
         <remarks>
-          <remarks>
-            <format type="text/markdown"><![CDATA[  
+          <format type="text/markdown"><![CDATA[  
 
 For example, if the value is 64, then 65,536 bytes are allowed for the maximum response headers' length.
 
          ]]></format>
-          </remarks>
         </remarks>
       </Docs>
     </Member>