Remove `ThreadLocals.enable` property in `main`

[vy]

As @ppkarwasz hints here in #2104,

I would just drop (and document) the support for the ThreadLocals.enable.

Unless I am mistaken it was only used in the recycling process, setting ThreadLocals.enable=false never disabled all thread locals. For example ThreadContext still used them. The ThreadLocals.enable property seems misleading and deprecated, since Recycler.factory replaces it.

Hence this ticket.