Describe the bug
When using the --format json flag with the --service flag, the output includes misconfigurations from other services.

To Reproduce
Steps to reproduce the behavior:

1. run trivy aws --service iam --format json
   a. suggest filtering the output with jq
   b. example:

trivy aws --service iam --format json | jq -r '.Results[]? | .Target'

2. Observe services other than IAM

Expected behavior

1. JSON output would include only the specified AWS service(s)