refactor: remove duplicated _construct_dest_file_path

[jx2lee]

Description

Refactor destination path construction for remote object storage uploads in the Astronomer Cosmos library.

• a new helper function construct_dest_file_path() in cosmos/io.py, responsible for normalizing and building destination paths for artifact upload.
• Remove duplicated _construct_dest_file_path logic from the local dbt operator class; instead reuse the shared helper to keep both upload and local operator path logic
• Add a unit test (tests/test_io.py) covering _construct_dest_file_path()

Related Issue(s)

closes #1746

Breaking Change?

No. This refactor preserves existing destination path semantics while changing internal implementation. Consumers invoking upload methods or operators will see no behavior change.

Checklist

• [ ] I have made corresponding changes to the documentation (if required)
• [x] I have added tests that prove my fix is effective or that my feature works

[jx2lee]

Thanks a lot for doing this refactor, @jx2lee. Changes like this really help the Cosmos code base be easier to maintain.

I provided minor feedback inline, and I'm happy for us to merge this change once the tests pass.

Please, rebase based on the main branch

@tatiana Thanks for waiting ! I was on a trip(🇯🇵), so update took a bit longer. Rebase is all done, too!

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