perf(grpcweb): remove useless HTTP HandlerFun wrapping (#9711) (#9721)

## Description

While looking into #9704 I found that we don't need to wrap grpc web handler into HTTP HandlerFun.

---

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(cherry picked from commit 609b19a)

Co-authored-by: Robert Zaremba <robert@zaremba.ch>

server/grpc/grpc_web.go

@@ -24,12 +24,9 @@ func StartGRPCWeb(grpcSrv *grpc.Server, config config.Config) (*http.Server, err
 	}
 
 	wrappedServer := grpcweb.WrapServer(grpcSrv, options...)
-	handler := func(resp http.ResponseWriter, req *http.Request) {
-		wrappedServer.ServeHTTP(resp, req)
-	}
 	grpcWebSrv := &http.Server{
 		Addr:    config.GRPCWeb.Address,
-		Handler: http.HandlerFunc(handler),
+		Handler: wrappedServer,
 	}
 
 	errCh := make(chan error)