Rename ASP.NET Core metrics

[JamesNK]

Fixes #48309
Fixes #48536

Renaming counters needs discussion in API review.

Summary of changes:

• Microsoft.AspNetCore.Hosting counters are prefixed with http-server
• Microsoft.AspNetCore.Http.Connections counters are prefixed with http-server
• Microsoft.AspNetCore.Servers.Kestrel counters are prefixed with kestrel
• Microsoft.AspNetCore.RateLimiting counters are prefixed with rate-limiting

Also, I'm unsure about Microsoft.AspNetCore.Http.Connections counters being prefixed by http-server. Are these counters used by anything other than SignalR? Should they include SignalR in the name instead of being very generic? @BrennanConroy

If the Microsoft.AspNetCore.Http.Connections counters are changed to not use the http-server prefix then we could consider making Microsoft.AspNetCore.Servers.Kestrel counters prefixed with http-server.

[JamesNK]

Blocked on API review.

[BrennanConroy]

Are these counters used by anything other than SignalR? Should they include SignalR in the name instead of being very generic?

They are for the ConnectionHandler layer. Not directly related to SignalR.
See https://github.com/dotnet/aspnetcore/tree/main/src/SignalR/samples/SocialWeather for an example, SignalR is not referenced at all.

Additionally, SignalR does not have a direct dependency on Http.Connections, it depends on the common abstractions from Connections.Abstractions that Http.Connections also relies on.

[JamesNK]

Alright. Do you have a better suggestion than http-server? It seems like this is about connection handling. The prefix could be connection-handler, but connection-handler-connection-duration feels a bit messy.

[JamesNK]

API review: #48536

[BrennanConroy]

I thought this was named signalr-http-transport-current-connections in API review.

[JamesNK]

Yes.

I just sent an email to API review to recommend current-negotiated-connections as the name:

When making this change, I found the new name has a couple of problems:

1. There's an existing current-connections event counter. The new proposed new signalr-http-transport-current-connections counter will start at a different time. That means the current-connections event counter and current-connections metric can have inconsistent values.
2. The proposed signalr-http-transport-current-connections is incremented when the connection has negotiated the transport and ends when the connection ends. That's a different time interval measured by signalr-http-transport-connection-duration. Someone could be confused why the times don't match.

I propose to rename what is currently "current-connections":

• current-connections -> current-negotiated-connections

[JamesNK]

I'm renaming it back to signalr-http-transport-current-connections. I'll make changes to get this name to "work" in a follow-up PR.