[8.x](backport #5616) Fix ownership of component specs in elastic-agent docker image

[mergify]

What does this PR do?

Fix ownership of components' spec files in <agent install dir>/data/elastic-agent-<commit>/components/*.yml from root:root to <user>:<user> where user is the default user the agent process will be started with

Why is it important?

To prevent permissions mismatches between component binaries and their spec yaml files under ../components

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

• Closes [Fleet]: Hosted fleet server gets unhealthy on 8.16 Snapshot. #5615

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?
• ...

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This is an automatic backport of pull request #5616 done by [Mergify](https://mergify.com).

[ycombinator]

Similar to #5616 (comment), this PR also needs to be force merged so Integrations Server on ESS can spin up without errors...