[msbuild/dotnet] Make 'LinkSdk' the default linker mode for Mac Catalyst when building for Release, and 'None' the default when building for Debug. Fixes #12264. (#12701)

Fixes https://github.com/xamarin/xamarin-macios/issues/12264.

dotnet/targets/Xamarin.Shared.Sdk.targets

@@ -1025,7 +1025,9 @@
 
 	<Target Name="_ComputeDefaultLinkMode" DependsOnTargets="_DetectSdkLocations">
 		<PropertyGroup>
-			<_DefaultLinkMode Condition="'$(_PlatformName)' == 'macOS' Or '$(_PlatformName)' == 'MacCatalyst'">None</_DefaultLinkMode> <!-- Linking is off by default for macOS and Mac Catalyst apps -->
+			<_DefaultLinkMode Condition="'$(_PlatformName)' == 'macOS'">None</_DefaultLinkMode> <!-- Linking is off by default for macOS apps -->
+			<_DefaultLinkMode Condition="'$(_PlatformName)' == 'MacCatalyst' And '$(Configuration)' == 'Release'">SdkOnly</_DefaultLinkMode> <!-- Default linking is on for release builds for Mac Catalyst apps -->
+			<_DefaultLinkMode Condition="'$(_PlatformName)' == 'MacCatalyst' And '$(Configuration)' != 'Release'">None</_DefaultLinkMode> <!-- Default linking is off for non-release builds for Mac Catalyst apps -->
 			<_DefaultLinkMode Condition="'$(_PlatformName)' != 'macOS' And '$(_PlatformName)' != 'MacCatalyst' And '$(_SdkIsSimulator)' == 'true'">None</_DefaultLinkMode> <!-- Linking is off by default in the simulator -->
 			<_DefaultLinkMode Condition="'$(_PlatformName)' != 'macOS' And '$(_PlatformName)' != 'MacCatalyst' And '$(_SdkIsSimulator)' != 'true'">SdkOnly</_DefaultLinkMode> <!-- Linking is SdkOnly for iOS/tvOS/watchOS apps on device -->
 		</PropertyGroup>