Add better logging in the indicator runner

[melange396]

https://github.com/cmu-delphi/covidcast-indicators/blob/main/_delphi_utils_python/delphi_utils/runner.py could have some more detail in its logging.

• add timing for (ie, around) core indicator method, and validation and flash steps (archive step already has some minimal summary info but could probably be improved)
• more detail for individual validation failure log messages, like threshold and reference/live values
• maybe move log line that prints "Completed indicator run" to a core location instead of replicating in each indicator?

and less generally:

• log around update_cache_file() in delphi_quidel_covidtest because the cache file is getting huge in prod (~180MB as of 2 aug 2023)