Rename collectPerfCounter to collectRuntimeMetrics

[danroth27]

Performance Counters were a Windows-specific .NET Framework feature: https://learn.microsoft.com/dotnet/framework/debug-trace-profile/performance-counters

In later versions of .NET, we switched to a cross-platform Runtime Metrics model: https://learn.microsoft.com/dotnet/core/diagnostics/migrate-from-windows-performance-counters

So, I think collectPerfCounters in Blazor should actually be collectRuntimeMetrics.