[DPC-4950] Add exception class to JSON log format

[ashley-weaver]

🎫 Ticket

https://jira.cms.gov/browse/DPC-4950

🛠 Changes

Adds exception class to JSON log format.

ℹ️ Context

Allows for faster log searches.

🧪 Validation

Test updated.

log example from smoke test:

{"timestamp":"2026-01-05T18:03:49.477+0000",
"level":"ERROR",
"thread":"RxComputationThreadPool-1",
"logger":"gov.cms.dpc.aggregation.engine.JobBatchProcessor",
"message":"Failed to retrieve Patient",
"exception":"ca.uhn.fhir.rest.server.exceptions.ResourceNotFoundException: No patient found with ID: \n\tat gov.cms.dpc.bluebutton.client.MockBlueButtonClient.formNoPatientException(MockBlueButtonClient.java:242)...",
"mdc":{"jobID":"e6fec28a-abe0-4906-88ad-2a738ce289b9","is_bulk":"true","organization_id":"0ab352f1-2bf1-44c4-aa7a-3004a1ffef12","aggregatorId":"fbc25203-a54e-4d88-83b5-d34134504962","batchID":"d7f12dae-db60-4d26-82ef-7f4575a14fe0","is_v2":"false"},
"environment":"local",
"application":"dpc-aggregation",
"version":"unknown_version",
"exceptionClass":"ResourceNotFoundException"}

[MEspositoE14s]

Looks like it'll do the job to me!

[MEspositoE14s]

LGTM 👍