hs-v2: Remove support for HSv2 on stable versions

Now that the HSv2 has been removed from the code base in 0.4.6.x series, we now need to proceed onto the next phase which is to eliminate it from the network.

We'll do this by removing the entry points into the HSv2 code relay side so:

• HSDir will stop accepting or serving v2 descriptors
• Introduction points wills top allowing introductions for v2.
• For Rendezvous points, we'll stop allowing it by refusing the TAP connection from the service side.

For client side:

• Disallow v2 service creation and client connections.

With these guards, we should be good with the removal of v2 in the network. We need this patch in 035 and 045 (the last two stable release we maintain with v2 support).