tastudio: don't autorestore if current frame remained valid

1b8b4b4926 removed an important bit of logic that set `_triggerAutoRestore` to false in certain cases. but simply putting the same line back there doesn't fix the problem, probably due to major refactorings over the years. so I'm adding it right into `GoToLastEmulatedFrameIfNecessary()` which is still called properly when it's needed. `JumpToGreenzone()` is kinda redundant now since it contains the same check, but it's used from the outside, and I didn't feel like refactoring this part.

src/BizHawk.Client.EmuHawk/tools/TAStudio/TAStudio.Navigation.cs

@@ -22,6 +22,10 @@ namespace BizHawk.Client.EmuHawk
 
 					GoToFrame(frame, false, false, OnLeftMouseDown);
 				}
+				else
+				{
+					_triggerAutoRestore = false;
+				}
 			}
 		}