Duplicate of RDS Logs Subscriptions

[ivan-pinatti]

Describe the Bug

The documentation/example for the aws-datadog-lambda-forwarder component shows adding RDSOSMetrics under cloudwatch_forwarder_log_groups, but this is redundant when forwarder_rds_enabled: true is set. Both mechanisms subscribe to the same RDSOSMetrics log group, which creates a duplicate CloudWatch Logs subscription.

Expected Behavior

When enabling forwarder_rds_enabled: true, the component should handle the subscription to RDSOSMetrics automatically. The example should not instruct users to add RDSOSMetrics again under cloudwatch_forwarder_log_groups.

Steps to Reproduce

1. Configure the component with both forwarder_rds_enabled: true and the example cloudwatch_forwarder_log_groups entry:

   components:
     terraform:
       datadog-lambda-forwarder:
         vars:
           forwarder_rds_enabled: true
           cloudwatch_forwarder_log_groups:
             rds-enhanced-monitoring:
               name: "RDSOSMetrics"
               filter_pattern: ""

2. Deploy with Atmos/Terraform.
3. Observe the error or duplicate subscription filters on the RDSOSMetrics log group.

Screenshots

N/A (error is a duplicate subscription on the same log group).

Environment (please complete the following information):

OS: Linux
Atmos: v1.180.0
Terraform: v1.12.1
Component: aws-datadog-lambda-forwarder

Additional Context

CloudWatch Logs only allows two subscription filters per log group. Having both forwarder_rds_enabled: true and the cloudwatch_forwarder_log_groups entry for RDSOSMetrics wastes one slot and introduces duplication/confusion.

The example in the documentation should be updated to omit RDSOSMetrics from cloudwatch_forwarder_log_groups when forwarder_rds_enabled: true is enabled.