Backport of add noswap to secretdir tmpfs into release/1.9.x

[hc-github-team-nomad-core]

Backport

This PR is auto-generated from #24645 to be assessed for backporting due to the inclusion of the label backport/1.9.x.

The below text is copied from the body of the original PR.

---

Description

This adds noswap mount option to the SecretDir mount.

Testing & Reproduction steps

• Create an allocation that triggers a secret dir creation

(having a hell of a time trying to get tests to run locally so I'm going to rely on GHA to run unit tests (fingers crossed))

Links

todo issue

Contributor Checklist

• Changelog Entry If this PR changes user-facing behavior, please generate and add a
  changelog entry using the make cl command.
• Documentation If the change impacts user-facing functionality such as the CLI, API, UI,
  and job configuration, please update the Nomad website documentation to reflect this. Refer to
  the website README for docs guidelines. Please also consider whether the
  change requires notes within the upgrade guide.

Reviewer Checklist

• Backport Labels Please add the correct backport labels as described by the internal
  backporting document.
• Commit Type Ensure the correct merge method is selected which should be "squash and merge"
  in the majority of situations. The main exceptions are long-lived feature branches or merges where
  history should be preserved.

---

Overview of commits

• f7b12dc