Integrate ModifyScalingGroup Action with existing GraphQL implementation

[jopemachine]

Objective

Complete Modify action with GraphQL integration and comprehensive tests.

Implementation Details

GraphQL mutation modification (~30 lines)

• ModifyScalingGroupInput → Updater conversion logic

• simple_db_mutate_returning_item → processors.scaling_group.modify.wait_for_complete()

  ScalingGroupOpts conversion logic cleanup (~20 lines)

• OptionalState / TriState conversion for nullable/non-nullable fields

  Additional Unit tests:

• test_modify_scaling_group_service.py (~80 lines)

• test_modify_scaling_group_repository.py (~100 lines)

• Edge case tests (not found, validation, etc.) (~50 lines)

Estimated Lines

~280 lines

Dependencies

• Story: ModifyScalingGroup Action - Updater Spec

Acceptance Criteria

• [ ] GraphQL mutation uses new processor pattern
• [ ] Input conversion properly handles all fields including ScalingGroupOpts
• [ ] OptionalState / TriState correctly applied to nullable vs non-nullable fields
• [ ] Edge cases tested (scaling group not found, invalid inputs)
• [ ] All unit tests pass
• [ ] Legacy simple_db_mutate_returning_item removed from ModifyScalingGroup

JIRA Issue: BA-3516