WIP: Use artifacts_size to check for build artifacts existence

Closed username-removed-506061 requested to merge fix/reduce-ci-build-artifacts-time into master

What does this MR do?

It uses Ci::Build#artifacts_size instead of doing actual artifact file existence. Testing on this repo's pipelines index, request time was reduced from ~8 seconds to ~3 seconds.

Are there points in the code the reviewer needs to double check?

The introduction of nullifying artifacts_size is pretty recent (around the end of last June), do we need a migration for old records?

Why was this MR needed?

To improve the speed of pages that depend on Ci::Build#artifacts? extensively (like pipelines index).

What are the relevant issue numbers?


Screenshots (if relevant)


Does this MR meet the acceptance criteria?