[Fix] Change flipper_id actor from Namespace to Group

What does this MR do and why?

Fixes a bug where custom work item types were not returned by the Provider when the work_item_configurable_types feature flag was enabled for a group.

Root Cause

The feature_available? method was using Namespace.actor_from_id(root_id) to check the feature flag, which creates a flipper_id of Namespace:143.

However, feature flags are enabled on Group objects which have a flipper_id of Group:143. This mismatch caused Feature.enabled? to return false even when the flag was properly enabled for the group.

Fix

Changed Namespace.actor_from_id(root_id) to Group.actor_from_id(root_id) to ensure the flipper_id matches how the feature flag is enabled.

# Before (bug)
Namespace.actor_from_id(143).flipper_id  # => "Namespace:143"
# After (fix)
Group.actor_from_id(143).flipper_id      # => "Group:143"

References

• Refactor Provider with indexed cache and Cached... (!226304 - merged)
• Slack thread

Screenshots or screen recordings

Create New Type	Before	After

How to set up and validate locally

# In rails console
group = Group.first

# 1. Ensure feature flag is disabled globally

Feature.disable(:work_item_configurable_types)

# 2. Create a custom type for testing

custom_type = WorkItems::TypesFramework::Custom::Type.create!(
  name: 'Test Bug Type',
  icon_name: 'bug',
  namespace: group
)

# 3. Verify custom types are NOT returned when FF is disabled

RequestStore.clear!
provider = WorkItems::TypesFramework::Provider.new(group)
types = provider.all_ordered_by_name.map(&:name)
# Should NOT include 'Test Bug Type'
types.include?('Test Bug Type')
# => false

# 4. Enable feature flag for the group only
Feature.enable(:work_item_configurable_types, group)

# 5. Verify custom types ARE returned when FF is enabled
RequestStore.clear!
provider = WorkItems::TypesFramework::Provider.new(group)
types = provider.all_ordered_by_name.map(&:name)
# Should include 'Test Bug Type'
types.include?('Test Bug Type')
# => true

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