Remove messaging header normalization

[AlchemyDing]

resolve issue

[SylvainJuge]

As described in the related issue #14502 this is a breaking change, so changing the default behavior should only be applied in 3.0.

I think you should thus split this in two steps:

• implement the change with an opt-in configuration option, so the default behavior remains the same: what this PR should provide
• in the next major, toggle the default to this new behavior, remove the configuration option and the now "legacy" behavior. Opening a dedicated issue and adding it the 3.0 milestone so we don't forget about this is recommended.

Here is an example of similar issues/PRs to deal with semconv breaking changes:

• semconv stable code #13860 : first step to introduce opt-in configuration without breaking default behavior
• Switch to stable code semconv attributes for 3.0 #14059 : clean-up and simplification step for 3.0 release

[AlchemyDing]

As described in the related issue #14502 this is a breaking change, so changing the default behavior should only be applied in 3.0.

I think you should thus split this in two steps:

• implement the change with an opt-in configuration option, so the default behavior remains the same: what this PR should provide
• in the next major, toggle the default to this new behavior, remove the configuration option and the now "legacy" behavior. Opening a dedicated issue and adding it the 3.0 milestone so we don't forget about this is recommended.

Here is an example of similar issues/PRs to deal with semconv breaking changes:

• semconv stable code #13860 : first step to introduce opt-in configuration without breaking default behavior
• Switch to stable code semconv attributes for 3.0 #14059 : clean-up and simplification step for 3.0 release

@SylvainJuge Thank you for your suggestion. I will make this PR as STEP 1

[otelbot-java-instrumentation]

🔧 The result from spotlessApply was committed to the PR branch.