[dotnet] Remove workaround for mono/linker#1304, which has now been fixed. (#9862)

dotnet/targets/Xamarin.Shared.Sdk.targets

@@ -226,10 +226,6 @@
 			</_CustomLinkerOptions>
 			<_ExtraTrimmerArgs>$(_ExtraTrimmerArgs) --custom-data "LinkerOptionsFile=$(_CustomLinkerOptionsFile)"</_ExtraTrimmerArgs>
 
-			<!-- Work around a linker issue: https://github.com/mono/linker/issues/1304 -->
-			<!-- System.Runtime.dll isn't always copied to the .app -->
-			<_ExtraTrimmerArgs>$(_ExtraTrimmerArgs) -p copy "System.Runtime"</_ExtraTrimmerArgs>
-
 			<!-- TrimMode specifies what the linker will do with framework assemblies -->
 			<TrimMode Condition="'$(_LinkMode)' == 'None'">copy</TrimMode> <!-- Don't use 'copyused', because that might still end up saving some assemblies, and if that's the platform assembly, it may break the partial static registrar -->
 			<TrimMode Condition="'$(_LinkMode)' == 'SdkOnly' Or '$(_LinkMode)' == 'Full'">link</TrimMode>