JIT: fix some instruction size estimates (#13432)
JIT: fix some instruction size estimates (#13432)

The jit might double-count the REX prefix for certain reg-reg moves, and
could overestimate the size of a code-referent LEA.

While the downstream emitter code can tolerate overestimates, it is better
not to have them.

Closes #13398

Also fixes overestimates for the following:

* `call reg`
* `call [reg]`
* `call [reg + disp-byte]`
* `cmp al,byte`

krk/coreclr,ruben-ayrapetyan/coreclr,poizan42/coreclr,JonHanna/coreclr,kyulee1/coreclr,poizan42/coreclr,JosephTremoulet/coreclr,krk/coreclr,parjong/coreclr,mmitche/coreclr,mmitche/coreclr,wtgodbe/coreclr,hseok-oh/coreclr,botaberg/coreclr,kyulee1/coreclr,hseok-oh/coreclr,rartemev/coreclr,yizhang82/coreclr,dpodder/coreclr,kyulee1/coreclr,AlexGhiondea/coreclr,AlexGhiondea/coreclr,ruben-ayrapetyan/coreclr,poizan42/coreclr,rartemev/coreclr,wateret/coreclr,cshung/coreclr,cshung/coreclr,AlexGhiondea/coreclr,krk/coreclr,krk/coreclr,poizan42/coreclr,parjong/coreclr,ruben-ayrapetyan/coreclr,JosephTremoulet/coreclr,mmitche/coreclr,cshung/coreclr,cshung/coreclr,JosephTremoulet/coreclr,yizhang82/coreclr,mmitche/coreclr,hseok-oh/coreclr,dpodder/coreclr,wtgodbe/coreclr,JosephTremoulet/coreclr,cshung/coreclr,yizhang82/coreclr,rartemev/coreclr,dpodder/coreclr,krk/coreclr,dpodder/coreclr,yizhang82/coreclr,yizhang82/coreclr,dpodder/coreclr,wtgodbe/coreclr,botaberg/coreclr,JonHanna/coreclr,cshung/coreclr,hseok-oh/coreclr,botaberg/coreclr,JonHanna/coreclr,JonHanna/coreclr,kyulee1/coreclr,rartemev/coreclr,JonHanna/coreclr,JosephTremoulet/coreclr,rartemev/coreclr,parjong/coreclr,dpodder/coreclr,yizhang82/coreclr,parjong/coreclr,mmitche/coreclr,wateret/coreclr,JosephTremoulet/coreclr,wateret/coreclr,krk/coreclr,botaberg/coreclr,wateret/coreclr,ruben-ayrapetyan/coreclr,botaberg/coreclr,ruben-ayrapetyan/coreclr,AlexGhiondea/coreclr,wtgodbe/coreclr,wtgodbe/coreclr,AlexGhiondea/coreclr,AlexGhiondea/coreclr,wateret/coreclr,wateret/coreclr,hseok-oh/coreclr,mmitche/coreclr,wtgodbe/coreclr,ruben-ayrapetyan/coreclr,poizan42/coreclr,hseok-oh/coreclr,rartemev/coreclr,parjong/coreclr,parjong/coreclr,kyulee1/coreclr,kyulee1/coreclr,JonHanna/coreclr,poizan42/coreclr,botaberg/coreclr