[10.0 swarm] Snapshot isn't created for fuel migration thread in case of a failure

[Sergey Novikov]

Detailed bug description:

The issue was found by

https://product-ci.infra.mirantis.net/job/10.0.system_test.ubuntu.fuel_master_migrate/223/testReport/fuel_tests.tests.test_fuel_migration/TestFuelMasterMigrate/test_compute_hard_restart

https://product-ci.infra.mirantis.net/job/10.0.system_test.ubuntu.fuel_master_migrate/223/testReport/fuel_tests.tests.test_fuel_migration/TestFuelMasterMigrate/test_compute_warm_restart

In case if a failure the snapshot is not created. we need to fix that for possibility of debugging

[Sergey Novikov (snovikov)]

the issue wasn't being reproduced during the latest runs