Add logging in UpdateJob to include checksum and bytesize

What does this MR do?

Add logging in UpdateJob to include checksum and bytesize to make troubleshooting issues more informed.

Why was this MR needed?

To make troubleshooting issues like the following less difficult: https://gitlab.com/gitlab-com/gl-infra/production/-/issues/6018

What's the best way to test this MR?

Passing pipeline should be sufficient. Unit tests confirm logging is occurring at the correct level.

What are the relevant issue numbers?

https://gitlab.com/gitlab-com/gl-infra/production/-/issues/6018

#28764 (closed)