Fix triggers

[pshriwise]

This PR resolves #2342 and #2343.

For #2342, The loop over tally scores in check_tally_trigger has been removed -- only the score index on the trigger is checked. A test was added ensuring that the addition of unrelated scores on a tally doesn't influence the number of batches needed to satisfy a tally trigger.

For #2343, the get_tally_uncertainty function returns an invalid result for a tally value if the mean is zero. This invalid result prompts the check_tally_trigger function to set the outgoing uncertainty-to-trigger threshold ratio value to infinity and exit early (no other tally result will produce a larger ratio, so we can do this safely). A ratio of infinity is used to trigger a different output to the console to indicate that the reason the trigger is unsatisfied is there was no contribution for the specified score.

Update: Adding a link to a CI run on my fork that contains only the first commit from this PR that adds the tests https://github.com/pshriwise/openmc/actions/runs/3850717720/jobs/6561182511

[aprilnovak]

This fixes the issue I was seeing - thanks for this really thorough fix!