Move build creation tracking from callbacks to pipeline chain

What does this MR do and why?

Move build creation telemetry tracking from after_commit to ..Chain::Metric

This prepares the codebase for some refactoring I am going to do in order to solve #588748, which will be done with bulk insert work.

No performance change or concern - same tracking operations, just moved from callback execution (during save!) to explicit loop (after transaction closes). The builds are already loaded in memory by the pipeline chain.

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