Feature Description:

TIN: number of microservice instances that are invoked in the current trace instance
Scope: Trace
Detail description:
    TIN is the number of microservice instances that are invoked in the current trace instance. For example, the invocation chain of the 
current trace instance is:
    A1 -> B1 -> C2 -> D1 -> E1
	                 -> B2
	(A1: "A" is microservice, "1" is instance id. D1 invokes E1 and B2 asynchronously.)
	In this case, the TIN of microservice B is 2, and the TIN of others microservice is 1.