sync-check: automatically recover after a state mismatch

[LesnyRumcajs]

Issue summary

Sometimes we get state mismatches which are not really linked to the merge commit it is failing on. See ChainSafe/forest#2958

Once a state mismatch occurs, Forest won't be able to get past the offending epoch (consider it a poor man's network upgrade). The only way to get over it is to import a new snapshot. It's a workaround we need to implement in the sync check.

Pseudocode:

if run_health_check.success?
  # all good, report successful run
else
  clear_db
end

Forest should automatically grab a fresh snapshot in case the DB is gone.

Other information and links

Similar issue: #93