Do something with advertised bandwidth distribution graphs

We currently have two graphs on advertised bandwidth distribution on Tor Metrics, Advertised bandwidth distribution and Advertised bandwidth of n-th fastest relays.

Unfortunately, the aggregation code that produces the data behind these graphs has always been somewhat painful to maintain. It was never written for the long term, it was rather a one-off analysis that we then made available on Tor Metrics. And now it's blocking a refactoring project where we want to share code between modules (#28342 (moved)). This is not a good situation to be in.

We discussed this briefly in Brussels, and I put some more thoughts into this today. Basically, I can see four ways for moving forward from here:

• Retain: We accept that this code is hard to maintain, but we retain it. We exclude the module from the refactoring project and keep it as legacy module. This seems like an ugly solution from a bit-rot perspective, unless we're only doing it for a limited time before removing the graphs, in which case this could work.
• Rewrite: We rewrite this module by designing a new database schema that is more flexible than the current approach. This is an awful amount of work, and we should only do it if we really think that these graphs are useful and will stay around for a long time.
• Remove: We remove the graph, because we don't see the need for it anymore. We can do this with a few weeks of warning, and we can archive the .csv files and graphs and put them into an attic kind of thing just like we're planning to do with Tor Messenger graphs (#26030 (moved)).
• Replace: We replace these two graphs with two that are much easier to provide, namely with consensus weight distribution graphs. I'm going to attach two samples shortly. The code changes are almost trivial, except that the resulting code will be much easier to maintain regarding the refactoring project mentioned earlier.