add server-side logging for db errors

[qian-squareup]

What and Why

Add server side logging for database errors in WriteResult function similar to logging for readError.

Testing

2025-06-10 06:03:16,063372 INFO 2025/06/10 06:03:16.063314 api_gomux.go:1258: DATABASE ERROR: write exception: write errors: [Document failed validation: {"failingDocumentId": {"$oid":"6847caa44258cdaabf0238ce"},"details": {"operatorName": "$jsonSchema","schemaRulesNotSatisfied": [{"operatorName": "required","specifiedAs": {"required": ["app","aws_arn","aws_account_id","aws_region","cache_node_id","replication_group_aws_arn"]},"missingProperties": ["aws_arn","aws_account_id","aws_region","cache_node_id","replication_group_aws_arn"]}]}}]