We currently save test artifacts as follows:

  "upload artifact":
    - command: archive.targz_pack
      params:
        target: ${upload_filename|wiredtiger.tgz}
        source_dir: ${upload_source_dir|wiredtiger}
        include:
          - "./**"

which by default saves the contents of the wiredtiger/ folder into a tarball, but not the wiredtiger folder itself. This means when we extract the tarball all of the folder contents are extracted into the current directory which is messy.

We should update this command - and the extraction logic - to instead pack the wiredtiger folder with its contents into the tarball so that extracting the tarball on a spawn hosts produces a single wiredtiger folder.