Solve Firecracker reboot issues

[nesitor]

Problem: If the frontend or a user send the request to reboot a Firecracker instance, it stops but doesn't start again.

Solution: Change method to restart it just stopping the process, cleaning the firecracker run files and starting it again.

[codecov]

Codecov Report

Attention: Patch coverage is 66.66667% with 1 line in your changes missing coverage. Please review.

Project coverage is 61.76%. Comparing base (35dd30a) to head (6471d14).

Files	Patch %	Lines
src/aleph/vm/controllers/__main__.py	0.00%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #658   +/-   ##
=======================================
  Coverage   61.75%   61.76%           
=======================================
  Files          68       68           
  Lines        5954     5955    +1     
  Branches      624      624           
=======================================
+ Hits         3677     3678    +1     
  Misses       2126     2126           
  Partials      151      151           

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[olethanh]

The lifecyle of the Execution in the different use case are not clear to me. Is the tear down ever called for Firecracker VM when it's running inside systemd?

[nesitor]

The lifecyle of the Execution in the different use case are not clear to me. Is the tear down ever called for Firecracker VM when it's running inside systemd?

Yes, previously to the PR, the Firecracker VM was removed completely on a service stop or restart. Now is only stopping the process and running it again. Only in the case that the instance is removed completely from the system should do the teardown process.