[ci] Migrate chaos test compute configs to new schema

[sai-miduthuri]

Summary

• Migrated 2 chaos test compute config files (compute_template.yaml and compute_template_gce.yaml) from legacy Anyscale compute config schema to the new SDK schema
• Added anyscale_sdk_2026: true flag to all 16 chaos test entries in release_tests.yaml

Config changes

• cloud_id -> cloud, ANYSCALE_CLOUD_ID -> ANYSCALE_CLOUD_NAME
• head_node_type -> head_node, worker_node_types -> worker_nodes
• min_workers/max_workers -> min_nodes/max_nodes
• use_spot: false -> market_type: ON_DEMAND
• advanced_configurations_json -> advanced_instance_config
• Flattened resources (removed custom_resources nesting, capitalized cpu -> CPU)
• GCE: replaced region + allowed_azs with zones
• Removed region, max_workers, and node name fields

Tests updated (16)

• chaos_many_tasks_{baseline,kill_raylet,iptable_failure_injection,terminate_instance}
• chaos_many_actors_{baseline,kill_raylet,iptable_failure_injection,terminate_instance}
• chaos_streaming_generator_{baseline,kill_raylet,iptable_failure_injection,terminate_instance}
• chaos_object_ref_borrowing_{baseline,kill_raylet,iptable_failure_injection,terminate_instance}

Test plan

• Both config files validated against ComputeConfig.from_yaml()
• Verify chaos tests pass on nightly run after merge

[gemini-code-assist]

Code Review

This pull request updates chaos test compute templates and release test configurations to the anyscale_sdk_2026 schema. Feedback identifies a schema error in compute_template.yaml where advanced_instance_config was incorrectly placed at the top level; it must be defined within each node configuration. Additionally, the zones field needs to be added to replace the removed region field for consistency with other templates.