Fix AwardEmoji namespace during work item moves

What does this MR do and why?

Moving a Work Item between projects copies its AwardEmoji rows from the source attributes. The copy updates awardable_id and awardable_type, but previously did not replace namespace_id, so copied rows retained the source namespace. The rows are then inserted with insert_all using that copied sharding key.

This change fixes a functional data-integrity issue in Work Item move data synchronization. It sets each copied row's namespace_id to target_work_item.namespace_id, keeping the sharding key and namespace lifecycle aligned with the target Work Item.

The regression test uses different source and target projects, preserves the existing copied-content assertion, and verifies that every copied AwardEmoji row uses the target namespace.

Validated against canonical master at e92cdba2c4c83fb0c7898741bf3c035ca3a621e3.

AI-assisted tooling was used during investigation and preparation. The contributor reviewed and validated the code, regression coverage, test results, and MR content before submission.

References

Closes #628128 (closed)

Screenshots or screen recordings

Before	After
N/A	N/A

How to set up and validate locally

Run the focused regression with both validation seeds:

RAILS_ENV=test mise exec -- bundle exec rspec spec/services/work_items/data_sync/widgets/award_emoji_spec.rb:29 --seed 17 --format documentation RAILS_ENV=test mise exec -- bundle exec rspec spec/services/work_items/data_sync/widgets/award_emoji_spec.rb:29 --seed 29 --format documentation

Run the complete affected spec and targeted RuboCop:

RAILS_ENV=test mise exec -- bundle exec rspec spec/services/work_items/data_sync/widgets/award_emoji_spec.rb --seed 17 --format documentation mise exec -- bundle exec rubocop app/services/work_items/data_sync/widgets/award_emoji.rb spec/services/work_items/data_sync/widgets/award_emoji_spec.rb

Before the fix, the focused regression failed twice for the predicted namespace mismatch (target/source: 8/6 and 12/10, exit status 1). After the fix, both focused runs passed with 1 example, the complete spec passed with 6 examples, and RuboCop reported no offenses.

A temporary uncommitted integration spec through WorkItems::DataSync::MoveService also passed with 1 example.

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