post 1.6.0 release : improve edot java release

[SylvainJuge]

this is a follow-up of release 1.6.0 which had a few issues, most of which relate to the changelog and documentation update

---

github release notes automation

The first attempt to automate changelog failed was a mixed success:

• update changelog before 1.6.0 #823
• release changelog automation #824
• try to fix changelog update #827

Now we have to deal with the following improvements

generated markdown is too verbose and contains useless junk

This file contains all changes which are not released yet.
<!--
 Note that the content between the marker comment lines (e.g. FIXES-START/END) will be automatically
 moved into the docs/release-notes markdown files on release (via the .ci/ReleaseChangelog.java script).
 Simply add the changes as bullet points into those sections, empty lines will be ignored. Example:

* Description of the change - [#1234](https://github.com/elastic/apm-agent-java/pull/1234)
-->

# Fixes
<!--FIXES-START-->

<!--FIXES-END-->
# Features and enhancements
<!--ENHANCEMENTS-START-->
* Add support for dynamic configuration options for 9.2 #818
* Switch upstream Opamp client #789

<!--ENHANCEMENTS-END-->
# Deprecations
<!--DEPRECATIONS-START-->

<!--DEPRECATIONS-END-->

# Breaking Changes
<!--BREAKING-CHANGES-START-->
* Switch to upstream instrumentation of openai by default #763

<!--BREAKING-CHANGES-END-->

This release is based on the following upstream versions:

* opentelemetry-javaagent: [2.20.1](https://github.com/open-telemetry/opentelemetry-java-instrumentation/releases/tag/v2.20.1)
* opentelemetry-sdk: [1.54.1](https://github.com/open-telemetry/opentelemetry-java/releases/tag/v1.54.1)
* opentelemetry-semconv: [1.37.0](https://github.com/open-telemetry/semantic-conventions-java/releases/tag/v1.37.0)
* opentelemetry-java-contrib: [1.49.0](https://github.com/open-telemetry/opentelemetry-java-contrib/releases/tag/v1.49.0)

• we need to move the upstream dependencies to the top or have them in a dedicated section
• when there are empty Fixes or Breaking Changes, then those sections should be omitted
• comments from the template should not be reused as-is, a clean markdown should be generated.

In order to fix the release notes, the github release notes have been modified manually to:

simplified release notes

This release is based on the following upstream versions:

* opentelemetry-javaagent: [2.20.1](https://github.com/open-telemetry/opentelemetry-java-instrumentation/releases/tag/v2.20.1)
* opentelemetry-sdk: [1.54.1](https://github.com/open-telemetry/opentelemetry-java/releases/tag/v1.54.1)
* opentelemetry-semconv: [1.37.0](https://github.com/open-telemetry/semantic-conventions-java/releases/tag/v1.37.0)
* opentelemetry-java-contrib: [1.49.0](https://github.com/open-telemetry/opentelemetry-java-contrib/releases/tag/v1.49.0)

## Features and enhancements

* Add support for dynamic configuration options for 9.2 #818
* Switch upstream Opamp client #789

## Breaking Changes

* Switch to upstream instrumentation of openai by default #763

1 hour wait for maven publication

The released artifact was available in maven central at the following URLs within minutes of the publication:

• https://repo.maven.apache.org/maven2/co/elastic/otel/elastic-otel-javaagent/1.6.0/
• https://repo1.maven.org/maven2/co/elastic/otel/elastic-otel-javaagent/1.6.0/

checking from local browser or using an equivalent curl command worked, however the job that waits on publication took about one hour to do the same : https://github.com/elastic/elastic-otel-java/actions/runs/18286517084/job/52062915861

Maybe there is a CDN involved, so this might not be something that we have some control over, however this means that it could become something that makes the job reach timeout and fail.

breaking changes documentation

See comment here.

The breaking changes page has been modified to make us use a template.

Using this template is not something we can easily automate as we store the changes in a simple markdown file with some known structure. Moving our "not yet released" changes to a structured format like YAML could probably help us