Fix dotnet-counters cli options to supply counter provider

dotnet-counters released a breaking change in v9.0.621003.

"Previously dotnet-counters allowed specifying a list of space separated counters prior to the -- token in collect/monitor mode. Counters must now be supplied explicitly in the --counters option as a list of comma-separated values." - https://github.com/dotnet/diagnostics/releases/tag/v9.0.621003

Author: dylanrichards

aspnetcore/grpc/diagnostics.md

@@ -416,7 +416,7 @@ gRPC client metrics are reported on `Grpc.Net.Client` event source.
 [dotnet-counters](/dotnet/core/diagnostics/dotnet-counters) is a performance monitoring tool for ad-hoc health monitoring and first-level performance investigation. Monitor a .NET app with either `Grpc.AspNetCore.Server` or `Grpc.Net.Client` as the provider name.
 
 ```console
-> dotnet-counters monitor --process-id 1902 Grpc.AspNetCore.Server
+> dotnet-counters monitor --process-id 1902 --counters Grpc.AspNetCore.Server
 
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