src: fix double free reported by coverity

[mhdawson]

Fix double free reported by coverity. ToBufferEndian() in node_i18n.cc was the only caller of Buffer::New() passing in a MaybeStackBuffer. Coverity reported a double free because there were paths in which the src buffer would be deleted by both the destruction of the MaybeStackBuffer and by the Buffer which was done even in failure cases for Buffer::New().

[mhdawson]

There are 3 similar coverity reports to this in node_i18n.cc. This is not new (initial report was in 2022) and should only have affected the error case which is unlikely.

2. Condition U_SUCCESS(*status), taking true branch.
210  if (U_SUCCESS(*status)) {
211    destbuf.SetLength(len);
   	3. freed_arg: ToBufferEndian frees destbuf.buf_. [[hide details](https://scan9.scan.coverity.com/eventId=9536861-3&modelId=9536861-1&fileInstanceId=124810153&filePath=%2Fsrc%2Fnode_i18n.cc&fileStart=107&fileEnd=120)]
212    ret = ToBufferEndian(env, &destbuf);
[/src/node_i18n.cc](https://scan9.scan.coverity.com/fileInstanceId=/124810153&defectInstanceId=/9536861&modelId=/9536861-1)
107MaybeLocal<Object> ToBufferEndian(Environment* env, MaybeStackBuffer<T>* buf) {
   	1. freed_arg: New frees parameter buf->buf_. [[show details](https://scan9.scan.coverity.com/eventId=9536861-4&modelId=9536861-2&fileInstanceId=124809979&filePath=%2Fsrc%2Fnode_internals.h&fileStart=187&fileEnd=205)]
108  MaybeLocal<Object> ret = Buffer::New(env, buf);
109  if (ret.IsEmpty())
110    return ret;
111
112  static_assert(sizeof(T) == 1 || sizeof(T) == 2,
113                "Currently only one- or two-byte buffers are supported");
114  if (sizeof(T) > 1 && IsBigEndian()) {
115    SPREAD_BUFFER_ARG(ret.ToLocalChecked(), retbuf);
116    SwapBytes16(retbuf_data, retbuf_length);
117  }
118
119  return ret;
120}
213  }
   	
CID 275315 (#1 of 1): Double free (USE_AFTER_FREE)
4. double_free: Calling ~MaybeStackBuffer frees pointer destbuf.buf_ which has already been freed. [[show details](https://scan9.scan.coverity.com/eventId=9536861-14&modelId=9536861-5&fileInstanceId=124810940&filePath=%2Fsrc%2Futil.h&fileStart=490&fileEnd=493)]
214  return ret;
215}

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/56151/

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/56195/

[mhdawson]

Landed in 9e87091