test: unify assertSnapshot common patterns #2965

Job	Run time
Build slim tarball	1m 40s
x86_64-linux: with shared libraries	2h 4m 22s
aarch64-darwin: with shared libraries	2h 52m 39s
aarch64-linux: with shared libraries	57m 57s
x86_64-darwin: with shared libraries	1h 28m 57s
	7h 25m 35s

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