Merge agentless scanning params into single AgentlessVulnerabilityScanning

[k3nz0]

Motivation

Most customers enable everything, keeping options as they are pre-filled.
By exposing less params, we simplify a bit the CloudFormation template.
It's more consistent with the AWS Side Panel view of the settings page where the 3 options are toggled together.
Prepares the ground for adding a new AgentlessComplianceScanning (not sure about the naming) for CSPM Agentless. (<- we remain consistent with the AWS side panel view, given that we plan to add a tile there too!)

Summary

• Replaces three separate parameters (AgentlessHostScanning, AgentlessContainerScanning, AgentlessLambdaScanning) with a single AgentlessVulnerabilityScanning parameter across all CloudFormation templates
• Updates the Lambda function (datadog_agentless_api_call.py) to fan out the single value to the three fine-grained API attributes (vuln_host_os, vuln_containers_os, lambda) that the Datadog API expects
• Simplifies Fn::Or conditions and rules in main_extended.yaml and main_extended_workflow.yaml from 4 branches to 2
• Aligns datadog_agentless_delegate_role_stackset.yaml custom resource with the new Lambda interface (single VulnerabilityScanning property instead of three)

Test plan

• All 16 unit tests pass (python3 -m unittest datadog_agentless_api_call_test -v)
• Grep confirms zero remaining references to AgentlessHostScanning, AgentlessContainerScanning, or AgentlessLambdaScanning
• Deploy stack and verify agentless scanning activation via Datadog API

🤖 Generated with Claude Code

[mohamed-challal]

LGTM, could you add the motivation of the change in the description to keep track?

[k3nz0]

LGTM, could you add the motivation of the change in the description to keep track?

Added to the PR description!

[ksirrah13]

❓question(nonblocking): Won't updating the parameters here cause it to break for customers using this to set those previous parameters? Or how is this template used right now and will there be followup changes to update how these parameters are being set?

[k3nz0]

❓question(nonblocking): Won't updating the parameters here cause it to break for customers using this to set those previous parameters? Or how is this template used right now and will there be followup changes to update how these parameters are being set?

Right now this is not something that is controllable from Datadog UI as the 3 toggles are already bundled in one.
Most of our customers keep the same values as they are. For the small subset of customers that want fine-grained controls it's still updatable through the API.