Use tracing span for maintenance

[vkgnosis]

I was looking at logs and reading about tracing::span . The spans are nice because they give context to why log messages are emitted. We already use them for for handling api requests so we know whether a log message originates from the process of handling a request and we give requests an id.
Likewise by adding a span here we will see which lower level log messages originate from maintenance.
I might add spans to a couple of other places in the future that I'm still thinking about.

Test Plan

run and observe the extra information (should be visible in CI)

[codecov-commenter]

Codecov Report

Merging #178 (69dae80) into main (412f36d) will increase coverage by 0.01%.
The diff coverage is 100.00%.

❗ Current head 69dae80 differs from pull request most recent head f49375e. Consider uploading reports for the commit f49375e to get more accurate results

@@            Coverage Diff             @@
##             main     #178      +/-   ##
==========================================
+ Coverage   64.81%   64.83%   +0.01%     
==========================================
  Files         185      185              
  Lines       38398    38398              
==========================================
+ Hits        24889    24895       +6     
+ Misses      13509    13503       -6     

[fleupold]

Awesome change! For debugging, it would be great to have a tracing span on the auction id in the solver (so that it's easy to filter logs of a particular "run")

[nlordell]

Agree that driver run loop by auction ID would be a nice span to have as well.