[8.15](backport #4939) feat: upgrade go agent to v2

[mergify]

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

---

This is an automatic backport of pull request #4939 done by Mergify.

[mergify]

Cherry-pick of d19603b has failed:

On branch mergify/bp/8.15/pr-4939
Your branch is up to date with 'origin/8.15'.

You are currently cherry-picking commit d19603bbcc.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	modified:   internal/pkg/agent/application/application.go
	modified:   internal/pkg/agent/application/coordinator/coordinator.go
	modified:   internal/pkg/agent/application/coordinator/coordinator_test.go
	modified:   internal/pkg/agent/application/dispatcher/dispatcher.go
	modified:   internal/pkg/agent/application/monitoring/server.go
	modified:   internal/pkg/agent/application/upgrade/artifact/download/composed/downloader.go
	modified:   internal/pkg/agent/application/upgrade/artifact/download/fs/downloader.go
	modified:   internal/pkg/agent/application/upgrade/step_download.go
	modified:   internal/pkg/agent/application/upgrade/upgrade.go
	modified:   internal/pkg/agent/cmd/enroll_cmd.go
	modified:   internal/pkg/agent/cmd/run.go
	modified:   internal/pkg/basecmd/version/cmd_test.go
	modified:   internal/pkg/fleetapi/ack_cmd.go
	modified:   internal/pkg/fleetapi/acker/fleet/fleet_acker.go
	modified:   internal/pkg/fleetapi/acker/lazy/lazy_acker.go
	modified:   pkg/component/fake/component/comp/apm.go
	modified:   pkg/component/runtime/manager.go
	modified:   pkg/component/runtime/manager_fake_input_test.go
	modified:   pkg/component/runtime/manager_test.go
	modified:   pkg/control/v1/server/server.go
	modified:   pkg/control/v2/control_test.go
	modified:   pkg/control/v2/server/server.go

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   NOTICE.txt
	both modified:   go.mod
	both modified:   go.sum

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

[elastic-sonarqube]

Quality Gate failed

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

See analysis details on SonarQube

[mergify]

This pull request has not been merged yet. Could you please review and merge it @kruskall? 🙏