[DevOps]: Refactor SimBoard log output based on log levels

### Is your feature request related to a problem?

Simboard logfile messages are overly verbose, voluminous, and difficult to parse plainly into easily identified categorical information. Variability in log output is not well-supported.

### Describe the solution you'd like

1. Implement a means of providing "log-level" adjustment upon process invocation. Among these, relegate to DEBUG or some high VERBOSE rating those messages that merely reiterate "decision=rejected reason=already_processed". These are 28% of all log output. Another category itemizes why a case/exec is rejected as "incomplete" (missing one or another file). Fully 70 % of log messages are these file-by-file individual decision messages. Another decision category to trim is "decision=deferred reason=max_cases_per_run" . The periodic "progress" lines could also be dispensed with except for a DEBUG mode.
2. Clearly identify selected categories of log message by code-words. Suggest for instance "CONFIG" for config declarations, CASE_SUMMARY for cases and RUN_SUMMARY for the entire run.
3. Make the last output summary human-readable, potentially one line per item similar to what is done in this [comment](https://github.com/E3SM-Project/simboard/pull/169#issuecomment-5512895919).

### Describe alternatives you've considered

None.

### Additional context

_No response_