Adjust `CubeTransaction` debug prints and tests. #186

Job	Run time
miri	2m 11s
no_std	42s
build (ubuntu, stable, locked, true)	59m 11s
build (windows, stable, locked, false)	29m 22s
build (macos, stable, locked, false)	21m 41s
build (ubuntu, nightly, locked, false)	33m 50s
build (ubuntu, beta, locked, false)	14m 38s
build (ubuntu, stable, latest, false)	23m 8s
build (ubuntu, stable, minimal, false)	18m 34s
deploy	7s
fuzz	18m 22s
	3h 41m 46s

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