testrunner: only provide `TimerResults` in executor tests when desire… #374

Job	Run time
build (ubsan, -DANALYZE_UNDEFINED=On, true, process, true)	45m 20s
build (tsan, -DANALYZE_THREAD=On, false, thread, false, --executor=thread --error-exitcode=0)	11m 36s
build (asan, -DANALYZE_ADDRESS=On, true, process, false)	13m 20s
	1h 10m 16s

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