Update C# Background Task samples for trimming and AOT - #419

Update C# Background Task samples for trimming and AOT#419

Dongle (dongle-the-gadget) wants to merge 1 commit into

microsoft:release/experimentalmicrosoft/WindowsAppSDK-Samples:release/experimentalfrom

dongle-the-gadget:bgtask-naotdongle-the-gadget/WindowsAppSDK-Samples:bgtask-naotCopy head branch name to clipboard