Update ubuntu-ci-x86_64.yaml: move jedi-run back to root filesystem

[climbfuji]

Description

Ran out of disk space on /mnt/addon, while there is plenty of space available on the root filesystem (at the moment ... this is only a duct-tape solution until we finally increase the disk space to something more than always close to the limit).

Issue(s) addressed

https://github.com/JCSDA/ufs-bundle/actions/runs/10363417834/job/28687005074

Dependencies

n/a

Impact

n/a

Checklist

• [x] I have performed a self-review of my own code
• [ ] I have made corresponding changes to the documentation
• [x] I have run the unit tests before creating the PR https://github.com/JCSDA/ufs-bundle/actions/runs/10369258662/job/28704609684?pr=72