TST: additional regression cases for slicing blockwise op (GH34421)
Adding the other case from https://github.com/pandas-dev/pandas/issues/34367 to the test as well (although also fixed by the PR, it was failing with a different error originally, so might be worth it to add as test case as well).

cc @jbrockmendel  
thanks @jorisvandenbossche  nice, thanks.  this has me wondering if we can use hypothesis to cover the space of block layouts