[ci] Disable status caching for manager-hosted jobs

[davidbiancolin]

This allows a fresh manager to be spun up when rerunning the test workflow. Previously you'd have to create new commit (which would invalidate the cache).

Related PRs / Issues

UI / API Impact

Verilog / AGFI Compatibility

Contributor Checklist

• Did you set dev as the base branch?
• Did you add Scaladoc to every public function/method?
• Did you add at least one test demonstrating the PR?
• Did you delete any extraneous prints/debugging code?
• Did you state the UI / API impact?
• Did you specify the Verilog / AGFI compatibility impact?

• (If applicable) Did you regenerate and publicly share default AGFIs?

• (If applicable) Did you mark the PR as "Please Backport"?
• (On merge) Did you update release notes in the dev-to-master PR ?

Reviewer Checklist (only modified by reviewer)

• Did you mark the proper release milestone?
• Did you check whether all relevant Contributor checkboxes have been checked?

[abejgonzalez]

LGTM