fix: shut down instance after workflow finishes

[abanuelo]

Description

As part of enhancing the simulator CI, we are introducing a condition for the stop_ec2_instance step that will get triggered regardless of success or failures of previous steps in the run to ensure that the instance is always stopped after a run.

Issue Link

Checklist

• I have tested the changes locally via pytest and/or other means
• I have added or updated relevant documentation
• I have autoformatted the code with black and isort
• I have added test cases (if applicable)

Additional Notes

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 91.36%. Comparing base (f2c61b1) to head (537fa7a).
Report is 8 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #293      +/-   ##
==========================================
+ Coverage   91.34%   91.36%   +0.02%     
==========================================
  Files          54       54              
  Lines       13535    13540       +5     
==========================================
+ Hits        12363    12371       +8     
+ Misses       1172     1169       -3     

see 5 files with indirect coverage changes

[dfremont]

Superseded by #310.