fix: unnecessary count() on RPC returning single #2102

Loadtest Results

param	v11.2.1	head	main
bytes_in.mean	1030.4712131596984	1030.4781470819157	1030.484761101992
bytes_in.total	24055320	23624742	23228157
bytes_out.mean	3848.3066312542837	3848.300619384105	3848.294884876447
bytes_out.total	89834870	88226140	86744415
duration	60003682501	60005817741	60013409986
errors.0	400 Bad Request	400 Bad Request	400 Bad Request
latencies.50th	965793	989334	996751
latencies.90th	2605113	2985827	2814638
latencies.95th	17933197	18183870	18658812
latencies.99th	18306157	18523876	19010459
latencies.max	39610459	35820979	45014731
latencies.mean	2569153	2616039	2661117
latencies.min	151700	154700	155299
latencies.total	59974316834	59975332960	59984251327
rate	389.042789158998	382.0629542781052	375.5993869579881
requests	23344	22926	22541
status_codes.200	12734	12506	12296
status_codes.201	2122	2084	2049
status_codes.204	6366	6252	6147
status_codes.400	2122	2084	2049
success	0.9090986977381761	0.9090988397452671	0.9090989752007451
throughput	353.6728326213622	347.3281975217177	341.45099251185184
wait	926399	827699	1058999