Log redacted config on config changes

[michel-laterman]

What is the problem this PR solves?

Debugging the fleet-server can be difficult as it is not clear what config it is running.

How does this PR solve the problem?

Output redacted configuration when an updated config is received.

How to test this PR locally

1. Compile a snapshot version of elastic-agent and fleet-server.
2. unzip elastic-agent snapshot.
3. Copy the fleet-server artifact and sha files to the elastic-agent downloads dir.
4. Install elastic-agent with a policy that only contains the fleet-server integration
5. Review logs to see redacted log config.

Checklist

• [] 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.

Related issues

• Closes Log all of fleet server configuration at startup #1626

[mergify]

This pull request is now in conflicts. Could you fix it @michel-laterman? 🙏
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 redact-config-log upstream/redact-config-log
git merge upstream/main
git push upstream redact-config-log

[elasticmachine]

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• Start Time: 2022-08-11T20:36:26.227+0000

• Duration: 12 min 33 sec

Test stats 🧪

Test	Results
Failed	0
Passed	304
Skipped	1
Total	305

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[mergify]

This pull request is now in conflicts. Could you fix it @michel-laterman? 🙏
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 redact-config-log upstream/redact-config-log
git merge upstream/main
git push upstream redact-config-log

[joshdover]

@michel-laterman Friendly bump on this one. @pierrehilbert should we be tracking this for 8.5?

[michel-laterman]

having this as cfg.Inputs causes one of the integration tests to fail.

[michel-laterman]

alternatively we can use the redactConfig call instead of redactServerCfg on lines 643 & 659 in configChangedServer (where it logs old/new config)

[ph]

LGTM for more debug options.