[obs-cloud-monitoring] Add undefined log.file.* fields breaking tests for filestream inputs

[bhapas]

What does this PR do?

Issue described in #7687

Checklist

• I have reviewed tips for building integrations and this pull request is aligned with them.
• I have verified that all data streams collect metrics or logs.
• I have added an entry to my package's changelog.yml file.
• I have verified that Kibana version constraints are current according to guidelines.

Related issues

• Relates [8.10] Undefined log.file.* fields breaking tests for filestream inputs #7687

[elasticmachine]

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• Start Time: 2023-10-03T14:29:22.403+0000

• Duration: 53 min 4 sec

Test stats 🧪

Test	Results
Failed	0
Passed	167
Skipped	0
Total	167

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🌐 Coverage report

Name	Metrics % (covered/total)	Diff
Packages	100.0% (4/4)	💚
Files	100.0% (6/6)	💚 11.864
Classes	100.0% (6/6)	💚 11.864
Methods	94.545% (156/165)	👍 2.355
Lines	96.122% (694/722)	👍 9.651
Conditionals	100.0% (0/0)	💚

[zmoog]

LGTM

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Package kubernetes - 1.46.0 containing this change is available at https://epr.elastic.co/search?package=kubernetes

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Package nginx_ingress_controller - 1.8.0 containing this change is available at https://epr.elastic.co/search?package=nginx_ingress_controller