test: the logging should be properly initialized when running multiple tests

[RolandSherwin]

Currently, if we have multiple unit tests with LogBuilder::init_single_threaded_tokio_test and if you run those tests at the same time, then only a single log file is created with all the logs being written there with overlap.

Use something like https://crates.io/crates/test-log. But preferably log them to a file, instead of stdout for easier debugging during CI.