reduce number of middleware handlers (#13546)

- combine similar looking functionalities into single
  handlers, and remove unnecessary proxying of the
  requests at handler layer.

- remove bucket forwarding handler as part of default setup
  add it only if bucket federation is enabled.

Improvements observed for 1kiB object reads.
```
-------------------
Operation: GET
Operations: 4538555 -> 4595804
* Average: +1.26% (+0.2 MiB/s) throughput, +1.26% (+190.2) obj/s
* Fastest: +4.67% (+0.7 MiB/s) throughput, +4.67% (+739.8) obj/s
* 50% Median: +1.15% (+0.2 MiB/s) throughput, +1.15% (+173.9) obj/s
```

cmd/test-utils_test.go

@@ -334,7 +334,7 @@ func UnstartedTestServer(t TestErrHandler, instanceType string) TestServer {
 	}
 
 	// Run TestServer.
-	testServer.Server = httptest.NewUnstartedServer(criticalErrorHandler{corsHandler(httpHandler)})
+	testServer.Server = httptest.NewUnstartedServer(setCriticalErrorHandler(corsHandler(httpHandler)))
 
 	globalObjLayerMutex.Lock()
 	globalObjectAPI = objLayer