Max length for Bytes escape hatch

[MOZGIII]

#2670 added a hard-coded limit to the max size of the Bytes struct; our runtime exceeds that size.

It is really a bad idea to have hard-coded limits like this, with no escape hatch; a better way to handle that would be an optional constructor argument for the max length with a default value; that way the said default value could be smaller, but adjusted when the context dictates it has to be bigger, or lifted entirely.

Like in our case - we are building some tooling to help us with runtime upgrade testing automation, and we really don't need any sort of fuss from the client-side like this at all - so we'd disable the max length and see where it gets us.