Remove serialization of pfx (#2721) (#2746)

Co-authored-by: Yuan-Ting Hsieh (謝沅廷) <[email protected]>

nvflare/lighter/impl/cert.py

@@ -116,11 +116,6 @@ def _build_write_cert_pair(self, participant, base_name, ctx):
             with open(os.path.join(dest_dir, "server.key"), "wb") as f:
                 f.write(serialize_pri_key(tmp_pri_key))
 
-        pkcs12 = serialization.pkcs12.serialize_key_and_certificates(
-            subject.encode("ascii"), pri_key, cert, None, serialization.BestAvailableEncryption(subject.encode("ascii"))
-        )
-        with open(os.path.join(dest_dir, f"{base_name}.pfx"), "wb") as f:
-            f.write(pkcs12)
         with open(os.path.join(dest_dir, "rootCA.pem"), "wb") as f:
             f.write(self.serialized_cert)