[8.14](backport #39860) filebeat: Fix flaky test case on macOS

[mergify]

Proposed commit message

This PR fixes following test cases which are flaky for macOS:

• tests/system/test_harvester.py::Test::test_debug_reader
• tests/system/test_crawler.py::Test::test_tail_files
• tests/system/test_crawler.py::Test::test_encodings
• tests/system/test_registrar.py::Test::test_restart_state_reset_ttl_no_clean_inactive
• tests/system/test_registrar.py::Test::test_restart_state_reset
• tests/system/test_registrar.py::Test::test_restart_state
• tests/system/test_registrar.py::Test::test_registry_file_update_permissions
• tests/system/test_shutdown.py::Test::test_shutdown

On MacOS, the FQDN lookup takes some time (~5 seconds) before signal handlers are set up

• the lingering FQDN lookup code is here
  To make sure that the tests are passed, we need to increase the timeout by few seconds in each of the failing cases.

You can view the full discussion https://elastic.slack.com/archives/C047NDNGUMU/p1717091056290869.

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.

Fixes #39613

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This is an automatic backport of pull request #39860 done by Mergify.

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