Add possibility to suppress errors in Tempest plugin cleanup

Now if something can not be cleaned up we get error and in case of CI job it is
'fail' of job. We should be able to suppress such errors.
Added config option 'suppress_errors_in_cleanup' that allows us to raise errors
when it is 'False' and log errors when it is 'True'.
Disable it by default.
Enable it for CI Tempest jobs.

Implements blueprint tempest-clean-up-suppress-errors

Change-Id: I03a39cc020f52d54211369c8f5cbfc2e14651a21
Merge "Add possibility to suppress errors in Tempest plugin cleanup"