Adopt high-performance logging (logger message source gen)

Log statement formatting comes with a cost. We should adopt [logger message source gen](https://docs.microsoft.com/en-us/dotnet/core/extensions/logger-message-generator) to offset this cost.

The summary of it is we will pay that cost only once for building the template for a given log instead of each individual log call.

Start with the linked logger message source generator documentation, then inspect the worker's existing log statements to determine the scope of adoption. Done means the applicable logging paths use source-generated messages and preserve current log output and behavior; add or update coverage where the affected logging behavior is tested.

Written by the indexing model from the issue text.