tests: fade-SLA on-air validation harness (measure-only) (#117) #241

Job	Run time
build (macos-latest, Release, gcc)	36s
build (windows-latest, Release, cl)	2m 32s
build (macos-latest, Release, clang)	38s
build-mingw	1m 28s
build (ubuntu-latest, Release, clang)	1m 0s
build (ubuntu-latest, Release, gcc)	47s
	7m 1s

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