fixed instance id in RpcServer (#322) #939

Job	Run time
Build up-cpp and dependencies	1m 29s
Run up-cpp tests	28s
Run Valgrind Memcheck	3m 27s
Run Valgrind ThreadCheck	2m 56s
Run Valgrind Helgrind	2m 50s
Run Valgrind DHAT	1m 52s
Lint C++ sources	1m 16s
CI status checks	2s
	14m 20s

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