Remove unstrument from malli.dev.cljs/start - favor hot reloading

[dvingo]

This was pointed out in this issue #695
That during (cljs) development if you're changing function definitions in a leaf namespace and do not re-eval the entry namespace where malli.dev.cljs/start! is called then you will get stale function values. This is because instrument captures the value of the function. The steps are:

1. instrument captures value of function, stores it in an atom.
2. developer changes definition of function (and code is hot-reloaded)
3. dev/start! runs and set!s previous function value from step 1.
4. developer is confused and code is broken.

So effectively hot reloading already is unstrument.

[ikitommi]

Thanks!