feat: upgrade go agent to v2

[kruskall]

What does this PR do?

Update the dependency to v2.

Why is it important?

go.elastic.co/apm v1 has been deprecated for a while.

Checklist

• My code follows the style guidelines of this project
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have made corresponding change to the default configuration files
• I have added tests that prove my fix is effective or that my feature works
• I have added an entry in ./changelog/fragments using the changelog tool
• I have added an integration test or an E2E test

Disruptive User Impact

How to test this PR locally

Related issues

Can be dropped from the dependency graph completely once elastic/e2e-testing#3845 is merged

Questions to ask yourself

• How are we going to support this in production?
• How are we going to measure its adoption?
• How are we going to debug this?
• What are the metrics I should take care of?
• ...

Closes #3404

[mergify]

This pull request does not have a backport label. Could you fix it @kruskall? 🙏
To fixup this pull request, you need to add the backport labels for the needed
branches, such as:

• backport-v./d./d./d is the label to automatically backport to the 8./d branch. /d is the digit

NOTE: backport-skip has been added to this pull request.

[elasticmachine]

Pinging @elastic/elastic-agent-control-plane (Team:Elastic-Agent-Control-Plane)

[jlind23]

@pchila I think this will also close #3404 right?

[pchila]

LGTM

[mergify]

This pull request is now in conflicts. Could you fix it? 🙏
To fixup this pull request, you can check out it locally. See documentation: https://help.github.com/articles/checking-out-pull-requests-locally/

git fetch upstream
git checkout -b drop/old-apm-agent upstream/drop/old-apm-agent
git merge upstream/main
git push upstream drop/old-apm-agent

[jlind23]

buildkite test it

[mergify]

This pull request is now in conflicts. Could you fix it? 🙏
To fixup this pull request, you can check out it locally. See documentation: https://help.github.com/articles/checking-out-pull-requests-locally/

git fetch upstream
git checkout -b drop/old-apm-agent upstream/drop/old-apm-agent
git merge upstream/main
git push upstream drop/old-apm-agent

[mergify]

This pull request is now in conflicts. Could you fix it? 🙏
To fixup this pull request, you can check out it locally. See documentation: https://help.github.com/articles/checking-out-pull-requests-locally/

git fetch upstream
git checkout -b drop/old-apm-agent upstream/drop/old-apm-agent
git merge upstream/main
git push upstream drop/old-apm-agent

[mergify]

This pull request is now in conflicts. Could you fix it? 🙏
To fixup this pull request, you can check out it locally. See documentation: https://help.github.com/articles/checking-out-pull-requests-locally/

git fetch upstream
git checkout -b drop/old-apm-agent upstream/drop/old-apm-agent
git merge upstream/main
git push upstream drop/old-apm-agent

[blakerouse]

Looks good, seems very mechanical change.

[elastic-sonarqube]

Quality Gate failed

Failed conditions
0.0% Coverage on New Code (required ≥ 40%)

See analysis details on SonarQube

[cmacknz]

Force merging past the test coverage requirement. This doesn't need unit tests.