NettyProcessor documentation and update

[zakkak]

• Add comments explaining the NettyProcessor native-image config
• Refactor HttpContentCompressorSubstitutions for consistency
• Remove obsolete runtime initialization of netty classes

Creating as draft to test in my fork.

[zakkak]

integration-tests/devtools fails due to #43662 being triggered at build time, see https://github.com/zakkak/quarkus/actions/runs/11144505742/job/30972921818#step:16:4357

I will revert https://github.com/quarkusio/quarkus/pull/43654/files#diff-305a2796c8e31d213fe9b9b4d2162ee30f45471241fa06e8741acf15c324a4b6R147 to keep BrotliOptions runtime initialized even when the library is present for the time being (to avoid the CI failures, despite it revealing an actual issue).

[zakkak]

Best reviewed per commit.

@franz1981 you might find the documentation part interesting/helpful.

[quarkus-bot]

Status for workflow Quarkus CI

This is the status report for running Quarkus CI on commit 058eb14.

✅ The latest workflow run for the pull request has completed successfully.

It should be safe to merge provided you have a look at the other checks in the summary.

You can consult the Develocity build scans.

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Flaky tests - Develocity

⚙️ Native Tests - Messaging1

📦 integration-tests/reactive-messaging-kafka

✖ io.quarkus.it.kafka.KafkaConnectorIT.testRequestReply - History

• iterable contents differ at index [2], expected: <reply-3> but was: <{"details":"Error id 23a0acc7-d4ab-4c9c-9414-89394c4e4e9c-1","stack":""}> - org.opentest4j.AssertionFailedError

org.opentest4j.AssertionFailedError: iterable contents differ at index [2], expected: <reply-3> but was: <{"details":"Error id 23a0acc7-d4ab-4c9c-9414-89394c4e4e9c-1","stack":""}>
	at io.quarkus.it.kafka.KafkaConnectorTest.testRequestReply(KafkaConnectorTest.java:112)
	at java.base/java.lang.reflect.Method.invoke(Method.java:569)
	at io.quarkus.test.junit.QuarkusTestExtension.interceptTestMethod(QuarkusTestExtension.java:810)
	at java.base/java.util.ArrayList.forEach(ArrayList.java:1511)
	at java.base/java.util.ArrayList.forEach(ArrayList.java:1511)

[gsmet]

Thanks, that's indeed a good idea given how complex this thing is!