Set DisableNETStandardCompatErrors (#6927)

Without setting this property, the NuGet pacakges will raise an error saying the libraries don't support net462.

These libraries work correctly on .NET Framework and the unit tests are passing. So disable the NuGet MSBuild error.

Author: eerhardt

src/Libraries/Microsoft.Extensions.ServiceDiscovery.Abstractions/Microsoft.Extensions.ServiceDiscovery.Abstractions.csproj

@@ -5,6 +5,7 @@
     <IsPackable>true</IsPackable>
     <Description>Provides abstractions for service discovery. Interfaces defined in this package are implemented in Microsoft.Extensions.ServiceDiscovery and other service discovery packages.</Description>
     <StrongNameKeyId>Open</StrongNameKeyId>
+    <DisableNETStandardCompatErrors>true</DisableNETStandardCompatErrors>
     <RootNamespace>Microsoft.Extensions.ServiceDiscovery</RootNamespace>
     <!-- https://github.com/dotnet/extensions/issues/6871 tracks enabling these -->
     <NoWarn>$(NoWarn);S1144;CA1002;S2365;SA1642;IDE0040;CA1307;EA0009;LA0003</NoWarn>

src/Libraries/Microsoft.Extensions.ServiceDiscovery/Microsoft.Extensions.ServiceDiscovery.csproj

@@ -5,6 +5,7 @@
     <IsPackable>true</IsPackable>
     <Description>Provides extensions to HttpClient that enable service discovery based on configuration.</Description>
     <StrongNameKeyId>Open</StrongNameKeyId>
+    <DisableNETStandardCompatErrors>true</DisableNETStandardCompatErrors>
     <!-- https://github.com/dotnet/extensions/issues/6871 tracks enabling these -->
     <NoWarn>$(NoWarn);CS8600;CS8602;CS8604;IDE0040;IDE0055;IDE0058;IDE1006;CA1307;CA1310;CA1849;CA2007;CA2213;SA1204;SA1128;SA1205;SA1405;SA1612;SA1623;SA1625;SA1642;S1144;S1449;S2302;S2692;S3872;S4457;EA0000;EA0009;EA0014;LA0001;LA0003;LA0008;VSTHRD200</NoWarn>
     <ImplicitUsings>enable</ImplicitUsings>