Add sync point between head node and login nodes + make DFSM check able to handle missing change-set

[gmarciani]

Description of changes

Cherry-picked from #2671

Tests

Tested as part of the original PR.

References

• Link to impacted open issues.
• Link to related PRs in other packages (i.e. cookbook, node).
• Link to documentation useful to understand the changes.

Checklist

• Make sure you are pointing to the right branch.
• If you're creating a patch for a branch other than develop add the branch name as prefix in the PR title (e.g. [release-3.6]).
• Check all commits' messages are clear, describing what and why vs how.
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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 76.48%. Comparing base (e75e22f) to head (43bdf19).

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #2672   +/-   ##
========================================
  Coverage    76.48%   76.48%           
========================================
  Files           22       22           
  Lines         2220     2220           
========================================
  Hits          1698     1698           
  Misses         522      522           

Flag	Coverage Δ
unittests	76.48% <ø> (ø)

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