Cherry-pick #25132 to 7.x: Keep http and logging config during enroll

[michalpristas]

Cherry-pick of PR #25132 to 7.x branch. Original message:

What does this PR do?

At the moment all configuration is discarded when agent enrolls to fleet.
This PR enables persistence of settings for logging and http (exposing metrics).
Without this cloud is not able to set http endpoint and collect metrics from agent and processes

Why is it important?

Cloud

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.next.asciidoc or CHANGELOG-developer.next.asciidoc.

[elasticmachine]

Pinging @elastic/agent (Team:Agent)

[elasticmachine]

Pinging @elastic/ingest-management (Team:Ingest Management)

[elasticmachine]

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Build stats

• Build Cause: Pull request #25168 opened

• Start Time: 2021-04-20T09:08:55.093+0000

• Duration: 91 min 55 sec

• Commit: bb19180

Test stats 🧪

Test	Results
Failed	0
Passed	6740
Skipped	24
Total	6764

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Test stats 🧪

Test	Results
Failed	0
Passed	6740
Skipped	24
Total	6764