Allow use of bash as a script interpreter

[iansltx]

For #24470.

Haven't tested E2E yet as this requires building a new fleetd (which can/should be released before the server changes get tagged...if the server gets released first a bash script execution will error out but won't have any ill effects otherwise) + testing with local TUF (and also means this needs to go in after fleetd is unfrozen).

Checklist for submitter

If some of the following don't apply, delete the relevant line.

• Changes file added for user-visible changes in changes/, orbit/changes/ or ee/fleetd-chrome/changes.
  See Changes files for more information.
• Added/updated automated tests
• A detailed QA plan exists on the associated ticket (if it isn't there, work with the product group's QA engineer to add it)
  • Try running a bash script on this fleet agent. In particular check that it can echo "$BASH_VERSION"
• Manual QA for all new/changed functionality
• For Orbit and Fleet Desktop changes:
  • Orbit runs on macOS, Linux and Windows. Check if the orbit feature/bugfix should only apply to one platform (runtime.GOOS).
  • Manual QA must be performed in the three main OSs, macOS, Windows and Linux.
  • Auto-update manual QA, from released version of component to new version (see tools/tuf/test).

The orbit upload-artifact action has been updated due to the old version getting deprecated:
https://github.com/fleetdm/fleet/actions/runs/12933328765/job/36071680332?pr=25449#step:1:24
https://github.blog/changelog/2024-04-16-deprecation-notice-v3-of-the-artifact-actions/

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 63.61%. Comparing base (07416c2) to head (d5be7af).

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #25449      +/-   ##
==========================================
+ Coverage   63.59%   63.61%   +0.02%     
==========================================
  Files        1622     1624       +2     
  Lines      155023   155309     +286     
  Branches     4003     4054      +51     
==========================================
+ Hits        98580    98796     +216     
- Misses      48661    48716      +55     
- Partials     7782     7797      +15     

Flag	Coverage Δ
backend	64.47% <100.00%> (+0.02%)	⬆️
frontend	53.08% <ø> (ø)

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[lucasmrod]

Let's duplicate this file on orbit/changes/

[lucasmrod]

LGTM!

(Reminder to not merge until we cut orbit 1.38.0, hopefully today!)