[Bug] ESQL schema field pruning #5306
Description
Describe the Bug
Currently the ESQL schemas are not being pruned correctly. See https://github.com/elastic/detection-rules/actions/runs/19307303532/job/55218108129?pr=5305#step:9:42.
What was once a non-nested flattened field
"azure.signinlogs.properties.authentication_details": "flattened",
gets merged with
"azure.signinlogs.properties.authentication_details.authentication_method": "keyword",
and becomes one. Pruning needs to happen again after merging.
To Reproduce
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Expected Behavior
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Screenshots
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Desktop - OS
None
Desktop - Version
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Additional Context
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