WT-8287 added scenarios for VLCS and FLCS to test_rollback_to_stable28; during testing we found that the FLCS scenario does not always trigger update restore eviction, especially when under load, and thus sometimes fails on the test machines. Consequently, we decided to disable the FLCS scenario: the test is apparently timing-dependent, and the marginal benefit of running it on FLCS is not that high.

It now seems that the VLCS scenario also fails sometimes in the same way, and it seems like the right thing to do, at least for the time being, is to disable it on VLCS as well, at least until we can find a way to make the test more reliable.