[SPARK-60022][BUILD] Upgrade Netty to 4.2.19.Final - #59266

What changes were proposed in this pull request?

This PR aims to upgrade Netty to 4.2.19.Final.

Why are the changes needed?

To bring the latest security and bug fixes:

• https://netty.io/news/2026/10/06/4-2-19-Final.html
• https://github.com/netty/netty/releases/tag/netty-4.2.19.Final (2026-10-06)

This release contains 16 security fixes, including the following in the modules used by Spark:

• Improper CRLF neutralization and request/response smuggling in io.netty:netty-codec-http
• Origin validation error and unbounded resource consumption in io.netty:netty-codec-http
• Unbounded resource consumption in io.netty:netty-codec-http2, io.netty:netty-codec-base, and io.netty:netty-codec-dns
• SNI routing bypass and improper access control in io.netty:netty-handler
• Input misinterpretation in io.netty:netty-codec-socks

It also contains the following bug fixes, among others:

• HTTP/2: Remove failed SETTINGS from ACK queue
• HTTP/2: Reserve promised stream before running the request verifier
• Guard ChunkedWriteHandler.doFlush() against re-entrant invocation from user code
• Guard against out-of-bounds reads when parsing ClientHello SNI extension
• Release Channel when SimpleChannelPool acquire is cancelled
• Make IoEventLoopGroup.isCompatible/isIoType side-effect free
• HttpUtil.getCharset() must accept whitespace before the next Content-Type parameter

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 5.5