kms: Expose API when bucket federation is enabled (#20143)

kms: Expose API available when bucket federation is enabled

When bucket federation feature is enabled, KMS API will not work, such
as `mc admin kms key list`

The commit will fix the issue by disabling bucket forwarding when this
is a KMS request.

cmd/generic-handlers.go

@@ -469,7 +469,7 @@ func setBucketForwardingMiddleware(h http.Handler) http.Handler {
 		}
 		if globalDNSConfig == nil || !globalBucketFederation ||
 			guessIsHealthCheckReq(r) || guessIsMetricsReq(r) ||
-			guessIsRPCReq(r) || guessIsLoginSTSReq(r) || isAdminReq(r) {
+			guessIsRPCReq(r) || guessIsLoginSTSReq(r) || isAdminReq(r) || isKMSReq(r) {
 			h.ServeHTTP(w, r)
 			return
 		}