Add partition_id to ci_pipeline_messages and backfill the values

Problem

In order to convert the primary key of ci_pipelines to include partition_id, we need to prepare the foreign keys in #436529 (closed) to include partition_id. However, there is no column partition_id on table ci_pipeline_messages.

Solution

• Add column partition_id with type bigint
• Backfill ci_pipeline_messages.partition_id using the values from ci_pipelines