[o365] Keep numbers as strings through to Elasticsearch

[chrisberkhout]

Proposed commit message

[o365] Keep numbers as strings through to Elasticsearch

By using `decode_json_string_numbers` instead of `decode_json` in the
CEL program, numbers will arrive at the ingest pipeline as strings
matching how they were formatted in the API's JSON string.

In most cases those values can be passed straight through to
Elasticsearch to be indexed as `long` or as `keyword`, so most
conversion processing has been removed.

There are two types of exceptions to this, handled by a normalization
script early in the pipeline:
- The `o365audit` input will still provide numbers, so where values need
  to be compared, we need to ensure we have a consistently formatted
  string. That is the case for the `RecordType` field.
- Some fields arrive from the API as numbers formatted with scientific
  notation, but they are indexed as `keyword` and should not use
  scientific notation there. That is the case for the other fields
  procesed by the normalization script.

To use `decode_json_string_numbers`, the minimum agent versions needed
to be updated from "^8.18.0 || ^9.0.0" to "^8.19.0 || ^9.1.0".

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.
• I have verified that any added dashboard complies with Kibana's Dashboard good practices

Related issues

• Relates o365: ensure that IDs are not rendered with e-notation #14428
• Relates o365: fix handling of file size values and numeric IDs #14289

[infra-vault-gh-plugin-prod]

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

[elasticmachine]

💚 Build Succeeded

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• Commit: 53608bd

cc @chrisberkhout

[efd6]

There are some cases here where the fields should be converted to numbers in the ingest pipeline as their semantics are numeric; ….ConditionsMatched.SensitiveInformation.{Confidence,Count,UniqueCount}, o365audit.ExchangeMetaData.{FileSize,RecipientCount} and file.size for example (there are others).