Add file size check for uploaded artifacts

What does this MR do and why?

It was noticed that there are certain (unexpected) scenarios where the size of the uploaded GCS artifact is not the same as the CI artifacts that was downloaded. Even in such a scenario, the code did not throw an error. This MR adds file size check to avoid such a scenario.

Fixes https://gitlab.com/gitlab-org/gitlab/-/issues/362690

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