Revert "Fix: Write response headers from copy of internal response's …

…headers (#797)"

This reverts commit d93a6e8.

pkg/abstractions/endpoint/buffer.go

@@ -468,15 +468,8 @@ func (rb *RequestBuffer) handleHttpRequest(req *request, c container) {
 
 	defer resp.Body.Close()
 
-	responseHeaders := make(http.Header)
-	for key, values := range resp.Header {
-		for _, value := range values {
-			responseHeaders.Add(key, value)
-		}
-	}
-
 	// Write response headers
-	for key, values := range responseHeaders {
+	for key, values := range resp.Header {
 		for _, value := range values {
 			req.ctx.Response().Writer.Header().Add(key, value)
 		}