Update ubuntu-ci-x86_64.yaml: move jedi-run back to root filesystem (#72)

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).

Author: climbfuji

.github/workflows/ubuntu-ci-x86_64.yaml

@@ -15,7 +15,7 @@ defaults:
     shell: bash
 
 env:
-  JEDI_ENV: /mnt/addon/jedi-run/ufs-bundle
+  JEDI_ENV: /home/ubuntu/ufs-bundle/jedi-run
 
 jobs:
   test-ufs-bundle: