[automation] update elastic stack version for testing 8.4.0-fa661330

[ghost]

What

Bump stack version with the latest one.

Further details

[start_time:Tue, 23 Aug 2022 12:16:12 GMT, release_branch:8.4, prefix:, end_time:Tue, 23 Aug 2022 18:23:50 GMT, manifest_version:2.1.0, version:8.4.0-SNAPSHOT, branch:8.4, build_id:8.4.0-fa661330, build_duration_seconds:22058]

[elasticmachine]

💚 Build Succeeded

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Build stats

• Start Time: 2022-08-24T05:16:04.068+0000

• Duration: 15 min 28 sec

Test stats 🧪

Test	Results
Failed	0
Passed	6134
Skipped	23
Total	6157

💚 Flaky test report

Tests succeeded.

🤖 GitHub comments

To re-run your PR in the CI, just comment with:

• /test : Re-trigger the build.

• /package : Generate the packages.

• run integration tests : Run the Elastic Agent Integration tests.

• run end-to-end tests : Generate the packages and run the E2E Tests.

• run elasticsearch-ci/docs : Re-trigger the docs validation. (use unformatted text in the comment!)

[elasticmachine]

🌐 Coverage report

Name	Metrics % (covered/total)	Diff
Packages	97.26% (71/73)	👍
Files	67.857% (152/224)	👍
Classes	68.161% (304/446)	👍
Methods	51.831% (835/1611)	👍
Lines	38.304% (9101/23760)	👎 -0.008
Conditionals	100.0% (0/0)	💚

[mergify]

Automatically approving mergify