Change the sample probability calculation processing so as to increase the coverage of the test.

[daisukenishino2]

Requirement

• https://github.com/OpenTouryoProject/AsynchronousProcessingService/blob/master/root/programs/CS/Samples/AsyncSvc_sample/AsyncSvc_sample/LayerB.cs#L257
• https://github.com/OpenTouryoProject/AsynchronousProcessingService/blob/master/root/programs/CS/Samples/AsyncSvc_sample/AsyncSvc_sample/LayerB.cs#L285
• https://github.com/OpenTouryoProject/AsynchronousProcessingService/blob/master/root/programs/VB/Samples/AsyncSvc_sample/AsyncSvc_sample/LayerB.vb