all: fix warning flagging the use of DeepEqual on error (#23624)

* core: fix warning flagging the use of DeepEqual on error

* apply the same change everywhere possible

* revert change that was committed by mistake

* fix build error

* Update config.go

* revert changes to ConfigCompatError

* review feedback

Co-authored-by: Felix Lange <fjl@twurst.com>

rpc/websocket_test.go

@@ -18,13 +18,13 @@ package rpc
 
 import (
 	"context"
+	"errors"
 	"io"
 	"net"
 	"net/http"
 	"net/http/httptest"
 	"net/http/httputil"
 	"net/url"
-	"reflect"
 	"strings"
 	"sync/atomic"
 	"testing"
@@ -69,7 +69,7 @@ func TestWebsocketOriginCheck(t *testing.T) {
 		t.Fatal("no error for wrong origin")
 	}
 	wantErr := wsHandshakeError{websocket.ErrBadHandshake, "403 Forbidden"}
-	if !reflect.DeepEqual(err, wantErr) {
+	if !errors.Is(err, wantErr) {
 		t.Fatalf("wrong error for wrong origin: %q", err)
 	}