[LV] Update remaining tests to use VPlan cost output (NFC). (#190038)
Move remaining tests checking legacy cost output to check the VPlan's
cost model output.
In some cases, checks become much more compact (checking a single
interleave group cost vs checking the individual members which all have
the group's cost). In some cases, auto-generation consistently checks
all relevant VFs.
PR: https://github.com/llvm/llvm-project/pull/190038