Refactor out copyConcurrency calculation in install.copyFiles()

[pchila]

What does this PR do?

Extract the copyConcurrency parameter out of copyFiles() function allows for a simpler function signature and removes a dependency on cli.IOStreams that was used only to output an error log. The functions copyFiles() and calculateCopyConcurrency() implement a better separation of concerns.

Why is it important?

General cleanliness of code and testability

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

Author's Checklist

• [ ]

How to test this PR locally

Related issues

• Closes Refactor out copy parallelism from install copyFiles() function #4284

Use cases

Screenshots

Logs

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?
• ...

[elasticmachine]

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

[elasticmachine]

Pinging @elastic/elastic-agent (Team:Elastic-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 cleanup-copy-files-during-install upstream/cleanup-copy-files-during-install
git merge upstream/main
git push upstream cleanup-copy-files-during-install

[elastic-sonarqube]

Quality Gate passed

The SonarQube Quality Gate passed, but some issues were introduced.

1 New issue
0 Security Hotspots
25.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube

[cmacknz]

👌