[docs] .NET 8 simplified dotnet-trace instructions

[jonathanpeppers]

Context: dotnet/diagnostics#4081
Context: dotnet/diagnostics#4090
Context: dotnet/runtime#88634
Context: dotnet/diagnostics#4337

Using the latest dotnet-trace tooling:

> dotnet tool list -g
Package Id                         Version                       Commands
--------------------------------------------------------------------------------------
dotnet-dsrouter                    7.0.447801                    dotnet-dsrouter
dotnet-gcdump                      7.0.447801                    dotnet-gcdump
dotnet-trace                       7.0.447801                    dotnet-trace

There is a simplified way to profile Android apps.

For an Android emulator:

> dotnet-dsrouter android-emu
Start an application on android emulator with one of the following environment variables set:
DOTNET_DiagnosticPorts=10.0.2.2:9000,nosuspend,connect
DOTNET_DiagnosticPorts=10.0.2.2:9000,suspend,connect
> adb shell setprop debug.mono.profile '10.0.2.2:9000,suspend,connect'
> dotnet-trace ps
3248  dotnet-dsrouter
> dotnet-trace collect -p 3248
...
[00:00:00:09]   Recording trace 3.2522   (MB)
Press <Enter> or <Ctrl+C> to exit...

For an Android device you will eventually be able to do dotnet-dsrouter android, except we found one issue.

Until dotnet/diagnostics#4337 is resolved, we can instead do:

> adb reverse tcp:9000 tcp:9001
> dotnet-dsrouter server-server -tcps 127.0.0.1:9001
> adb shell setprop debug.mono.profile '127.0.0.1:9000,suspend,connect'
> dotnet-trace ps
> dotnet-trace collect -p 3248

We can also now use dotnet-gcdump! Instead of dotnet-trace collect -p, you can simply do:

> dotnet-gcdump collect -p 3248

In both cases these tools know that the process ID is a dotnet-dsrouter process and to do the right thing.