Fix regression for handling `mouseenter`/`mouseleave` events introduced by #33310...

Fix regression for handling `mouseenter`/`mouseleave` events introduced by #33310 (#33679)

* test: update spec for sibling adjacent mouseenter/mouseleave events

there is a regression introduced by #33310 - this would have catched that

* fix: fixup regression for mouseenter/mouseleave events introduced by #33310

the old logic only worked for parent-child movement since it checked for the relatedTarget to contain the delegateTarget - this should be fixed with this

Co-authored-by: XhmikosR <xhmikosr@gmail.com>