### What changes were proposed in this pull request?

This PR aims to upgrade `Netty` to 4.2.15.Final.

### Why are the changes needed?

To bring the latest bug fixes:

- https://netty.io/news/2026/06/01/4-2-15-Final.html
  - [CVE-2026-48059](GHSA-h2qv-fj59-j46j): memory exhaustion in io.netty:netty-codec-haproxy (high).
  - [CVE-2026-47691](GHSA-5pvg-856g-cp85): DNS cache poisoning in io.netty:netty-resolver-dns (high).
  - [CVE-2026-50560](GHSA-563q-j3cm-6jxm): DDoS in io.netty:netty-codec-http2.
  - [CVE-2026-50011](GHSA-5w86-c3rq-vjj7): memory exhaustion in io.netty:netty-codec-redis (high).
  - [CVE-2026-44250](GHSA-3244-j874-rhc2): memory exhaustion in io.netty:netty-codec-redis (high).
  - [CVE-2026-44890](GHSA-6ghj-frrj-jjj3): memory exhaustion in io.netty:netty-codec-redis (high).
  - [CVE-2026-50009](GHSA-cq4q-cv5g-r8q5): information disclosure and denial of service in io.netty:netty-codec-classes-quic.
  - [CVE-2026-44249](GHSA-3qp7-7mw8-wx86): IPv6 subnet filter bypass in io.netty:netty-handler (high).
  - [CVE-2026-50020](GHSA-hvcg-qmg6-jm4c): request smuggling in io.netty:netty-codec-http.
  - [CVE-2026-44892](GHSA-c2rx-5r8w-8xr2): memory exhaustion in io.netty:netty-codec-http3 (high).
  - [CVE-2026-44893](GHSA-cc37-9q2j-3hfv): memory leak in io.netty:netty-codec-haproxy (high).
  - [CVE-2026-44894](GHSA-cmm3-54f8-px4j): traffic amplification in io.netty:netty-codec-classes-quic (high).
  - [CVE-2026-50010](GHSA-c653-97m9-rcg9): TLS hostname verification accidentally disabled in io.netty:netty-handler (high).
  - [CVE-2026-45673](GHSA-xmv7-r254-6q78): DNS cache poisoning in io.netty:netty-resolver-dns.
  - [CVE-2026-45416](GHSA-x4gw-5cx5-pgmh): excessive memory usage from SNIHandler in io.netty:netty-handler (high).
  - [CVE-2026-45536](GHSA-w573-9ffj-6ff9): file descriptor leak in io.netty:netty-transport-native-epoll and io.netty:netty-transport-native-kqueue.
  - [CVE-2026-45674](GHSA-676x-f7gg-47vc): DNS cache poisoning in io.netty:netty-resolver-dns (high).
  - [CVE-2026-46340](GHSA-5xrh-qmmq-w6ch): memory exhaustion in io.netty:netty-transport-sctp (high).
  - [CVE-2026-47244](GHSA-5x3r-wrvg-rp6q): denial of service in io.netty:netty-codec-http2.
  - [CVE-2026-48006](GHSA-6jv9-x5w9-2ccm): memory exhaustion in io.netty:netty-codec-redis (high).
  - [CVE-2026-48748](GHSA-4grm-h2qv-h6w6): memory exhaustion in io.netty:netty-codec-http3 (high).
  - [CVE-2026-48043](GHSA-c2gf-v879-257j): memory exhaustion in io.netty:netty-codec-http2.
  - netty/netty#16836
  - netty/netty#16810
  - netty/netty#16853
  - netty/netty#16837
  - netty/netty#16844
  - netty/netty#16850
  - netty/netty#16890

- https://netty.io/news/2026/05/20/4-2-14-Final.html
  - netty/netty#16747
  - netty/netty#16759
  - netty/netty#16767
  - netty/netty#16781
  - netty/netty#16788

### Does this PR introduce _any_ user-facing change?

No.

### How was this patch tested?

Pass the CIs.

### Was this patch authored or co-authored using generative AI tooling?

Generated-by: Claude Opus 4.8

Closes apache#56373 from dongjoon-hyun/SPARK-57320.

Authored-by: Dongjoon Hyun <dongjoon@apache.org>
Signed-off-by: Dongjoon Hyun <dongjoon@apache.org>