Remove arch-specific tags for .NET Monitor

See [Announcement: New tagging scheme for .NET Monitor, Aspire Dashboard, and samples (#5961)](https://github.com/dotnet/dotnet-docker/discussions/5961) and [Undocument arch-specific tags on .NET appliance images (#5946)](https://github.com/dotnet/dotnet-docker/issues/5946) for context.

This issue tracks removing the arch-specific tags for .NET Monitor in the .NET 10 timeframe.