Nearly all configurations in the System.ComponentModel.Annotations
package weren't built live anymore and just redistributed from older
packages. Except for the netstandard2.0 configuration, the package
didn't receive any changes. As the library is exposed as part of the
shared framework, a reference to the package on .NETCoreApp isn't
necessary and will be ignored by the SDK.

Based on these reasons, dead-ending the package to remove the burden
of maintaining the harvesting of old configurations.

Contributes to https://github.com/dotnet/runtime/issues/47530