[Coverage] Resurrect Branch:FalseCnt in SwitchStmt that was pruned in #112694 (#120418)
I missed that FalseCnt for each Case was used to calculate percentage in
the SwitchStmt. At the moment I resurrect them.
In `!HasDefaultCase`, the pair of Counters shall be `[CaseCountSum,
FalseCnt]`. (Reversal of before #112694)
I think it can be considered as the False count on SwitchStmt.
FalseCnt shall be folded (same as current impl) in the coming
SingleByteCoverage changes, since percentage would not make sense.