testrunner: do not use global check instances #19793

Job	Run time
build_make (ubuntu:24.04)	4m 18s
build_cmake (ubuntu:25.10, true, true)	5m 1s
build_make (ubuntu:25.10)	4m 26s
build_cmake (ubuntu:24.04, true, true)	4m 23s
build_cmake (alpine:3.23, false, false)	4m 19s
build_make (alpine:3.23)	5m 7s
	27m 34s

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