Add project_id sharding key to p_ci_pipeline_artifact_states

What does this MR do and why?

Adds project_id sharding key to p_ci_pipeline_artifact_states table with index, foreign key, trigger, and batched background migration.

References

Closes #587555 (closed)

How to set up and validate locally

Run the migrations and verify the column, index, and FK exist on the table.

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