V2 Qwik router viewTransition defaults to true

[maiieul]

It can feel slower sometimes and cause timeout errors if the browser devtools has "disableCache" set.

I think we should disable it by default and have it be opt in.

[wmertens]

Actually, it's already enabled by default in v1, so that would be a slightly breaking change.

I think that the difference between v1 and v2 docs is that the v1 docs disable the CSS for it 🤔