Revert "Fix isolation test to be less timing-dependent"
This reverts commit
2268e6afd596. It turned out that inconsistency in
the report is still possible, so go back to the simpler formulation of
the test and instead add an alternate expected output.
Discussion: https://postgr.es/m/
20180103193728.ysqpcp2xjnqpiep7@alvherre.pgsql