[automation] update elastic stack version for testing 8.4.2-4457f478

[apmmachine]

What

Bump stack version with the latest one.

Further details

[start_time:Wed, 14 Sep 2022 00:16:00 GMT, release_branch:8.4, prefix:, end_time:Wed, 14 Sep 2022 04:59:09 GMT, manifest_version:2.1.0, version:8.4.2-SNAPSHOT, branch:8.4, build_id:8.4.2-4457f478, build_duration_seconds:16989]

[elasticmachine]

💚 Build Succeeded

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Build stats

• Start Time: 2022-09-14T05:21:53.092+0000

• Duration: 15 min 21 sec

Test stats 🧪

Test	Results
Failed	0
Passed	6109
Skipped	23
Total	6132

💚 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	97.222% (70/72)	👍
Files	67.713% (151/223)	👍
Classes	68.172% (302/443)	👍
Methods	51.782% (828/1599)	👍
Lines	38.159% (9023/23646)	👎 -0.025
Conditionals	100.0% (0/0)	💚

[mergify]

Automatically approving mergify