ti_misp: Fix ECS date mapping on threat fields.

[kcreddy]

Proposed commit message

Fix ECS date mapping for threat fields.

ecs@mappings component template is missing threat fields 
mapped as date. Example: fields such as first_seen, last_seen, 
modified_at are being mapped as keyword in transform's source 
datastream-backed indices. The transform's destination indices
are not effected as they are not datastream-backed and mappings
are explicitly defined as date. This causes field type conflicts.

   - Explicitly add ECS threat fields that are of type date into 
     source data-stream backed fields.

   - Fix first_seen, last_seen date processors with microseconds.

   - Add missing first_seen, last_seen fields.

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 [Threat Intelligences Utilities]: Intelligence Dashboard in Elastic Security Broken #10612

[elastic-sonarqube]

Quality Gate failed

Failed conditions
71.6% Coverage on New Code (required ≥ 80%)

See analysis details on SonarQube

[elasticmachine]

💚 Build Succeeded

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• Commit: 96bd055

[elasticmachine]

Pinging @elastic/security-service-integrations (Team:Security-Service Integrations)

[elasticmachine]

Package ti_misp - 1.35.1 containing this change is available at https://epr.elastic.co/search?package=ti_misp