More specific logging configuration in test environment

[RitaMAllenCA]

The testing environment currently produces slightly spammy logs, due to too many unrelated crates producing log messages (e.g. hyper and other third-party crates). This is likely due to logging being setup with a catchall setting like RUST_LOG=debug.
To remedy, the default configuration should be something like RUST_LOG=warn,casper_node_launcher=debug,casper_node=debug
Furthermore it would be good to include the log configuration in the dumps created after tests. Since these settings are likely set in the systemd unit file, it would make sense to include said unit file in the archive.

[RitaMAllenCA]

@sacherjj @cspramit I logged this here so we don't lose track. Sai does not appear to have an account. Where should SRE work be logged? Can you send me a link to the JIRA instance being used to track the work? I can certainly put the work in there. Please advise.