Add changelog for default ES compression

[faec]

Changelog-only PR. Adds an entry for enabling compression by default in Elasticsearch outputs, which is an update that is propagating to Agent now that elastic/beats#36681 changed the default for all beats.

[elasticmachine]

Pinging @elastic/elastic-agent (Team:Elastic-Agent)

[mergify]

This pull request does not have a backport label. Could you fix it @faec? 🙏
To fixup this pull request, you need to add the backport labels for the needed
branches, such as:

• backport-v./d./d./d is the label to automatically backport to the 8./d branch. /d is the digit

NOTE: backport-skip has been added to this pull request.

[elasticmachine]

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• Start Time: 2023-10-03T20:02:06.006+0000

• Duration: 26 min 33 sec

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Test	Results
Failed	0
Passed	6465
Skipped	59
Total	6524

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[elasticmachine]

🌐 Coverage report

Name	Metrics % (covered/total)	Diff
Packages	98.78% (81/82)	❕
Files	66.0% (198/300)	❕
Classes	64.991% (362/557)	❕
Methods	52.425% (1146/2186)	❕
Lines	38.088% (13065/34302)	❕
Conditionals	100.0% (0/0)	💚

[elastic-sonarqube]

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[jlind23]

Tests failures are unrelated force merging this then.

[jlind23]

@lucabelluccini FYI from 8.11 on we will change the default compression for ES output to 1.