reactor: fix reserve_io_control_blocks config name in error message #821

Job	Run time
Test with C++20 modules enabled / test	11m 51s
Test with DPDK enabled / test	12m 9s
Test (clang++, C++20, dev) / test	4m 50s
Test (clang++, C++20, debug) / test	7m 54s
Test (clang++, C++20, release) / test	5m 34s
Test (clang++, C++23, debug) / test	7m 31s
Test (clang++, C++23, dev) / test	5m 6s
Test (clang++, C++23, release) / test	16m 1s
Test (g++, C++20, debug) / test	11m 41s
Test (g++, C++20, dev) / test	4m 36s
Test (g++, C++20, release) / test	8m 21s
Test (g++, C++23, debug) / test	12m 19s
Test (g++, C++23, dev) / test	4m 51s
Test (g++, C++23, release) / test	10m 6s
	2h 2m 50s

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