Add bucket size hints to histograms

[JamesNK]

Histograms use buckets to efficiently store data. Good data requires good histogram bucket sizes, customized to an instrument. Hacks were required in .NET 8 to be in a good place here.

A feature to improve this in System.Diaganostics.Metrics is planned for .NET 9. We need to update our metrics to use the new API where appropriate and remove hacks.