DAOS-16362 pydaos: remove execute perm bit on checkpoint files

[enakta]

There's no need to set execute permission bit for the checkpoint files.

Probably it was set by mistake.

Features: pytorch

Steps for the author:

• Commit message follows the guidelines.
• Appropriate Features or Test-tag pragmas were used.
• Appropriate Functional Test Stages were run.
• At least two positive code reviews including at least one code owner from each category referenced in the PR.
• Testing is complete. If necessary, forced-landing label added and a reason added in a comment.

After all prior steps are complete:

• Gatekeeper requested (daos-gatekeeper added as a reviewer).

[github-actions]

Ticket title is 'pytorch checkpoint module'
Status is 'Resolved'
https://daosio.atlassian.net/browse/DAOS-16362

[daosbuild3]

Test stage Functional Hardware Medium MD on SSD completed with status FAILURE. https://jenkins-3.daos.hpc.amslabs.hpecorp.net//job/daos-stack/job/daos/view/change-requests/job/PR-17651/1/execution/node/1362/log