run_import: fix cover statics
Failure rate and other statistics based on RunFilterStatistic
are not
calculated correctly because RunFilterStatistic
is only created for
test_results which are failures (is_failure returns true). To fix that
we have to itterate over all the results and check coverage of filters.
Unfortunatelly this may result in worsening of the import duration.
Example:
In case of filter -> 'status_name = "abort"' statistic will be created for:
- test result matching filters (status_name = "abort")
- test results not matching filters but which are failures (status_name = "fail", "timeout" etc.)
Statistic won't be created for test result with status name "pass".