The pinoIntegration previously captured error events with no context beyond the error itself. For logger.error(err, 'Failed to do X'), the log message was dropped entirely, as were all other fields on the log line (child logger bindings, merge object fields like request IDs, the logger name).

This PR attaches a pino context to events captured via error.levels — on both the captureException and captureMessage paths — containing:

• the formatted log message, stored under the logger's resolved messageKey (msg by default), so user merge fields named e.g. message are never clobbered
• all remaining fields of the serialized log line (child logger bindings, merge object fields, logger name, ...)

The serialized error itself is excluded from the context since it is already captured as the event exception, and the level/time/pid/hostname housekeeping fields are stripped, matching the existing log capture path. Custom messageKey/errorKey configurations are respected, and the fields are taken from the serialized log line, so pino redaction/serializers still apply.

Example: logger.error({ err, requestId: 'abc-123' }, 'Failed to do X') now produces an error event with

{
  "contexts": {
    "pino": {
      "name": "myapp",
      "requestId": "abc-123",
      "msg": "Failed to do X"
    }
  }
}

Fixes #17969