fix: storage: Remove temp fetching files after failed fetch

[magik6k]

Related Issues

Proposed Changes

This fixes an issue where partially fetched files would be left in fetching directories when the fetch operation failed, with logs like this:

fetch error http://10.99.16.4:3456/remote/cache/s-t02620-5917 (storage 86f06f35-dee0-405b-8c60-e508a35b5a2e) -> /data/3/store/cache/fetching/s-t02620-5917: write /data/3/store/cache/fetching/s-t02620-5917/sc-02-data-layer-7.dat: no space left on device

Additional Info

Should result with far less garbage data after fetch operations fail. Should also make the experience of running out of disk space while sealing much better.

• Test that it works

Checklist

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