Renumber experimental reconnection TLVs

[rustyrussell]

We used low numbers here, and we should change them to the experimental range: the spec is starting to add them and we will clash.

[sangbida]

Hey, I was wondering if I could pick this up as my first issue?

[rustyrussell]

Oh, it's a tricky one! You have to rework the spec, then rework the spec patch in the tree, then fix up any tests. I'm wondering if it's worth supporting at all (since we disabled it for the 25.05 release anyway), since the spec process seems to have gone with a more ambitious upgrade method.

[sangbida]

Ah I see! I'm still happy to pick it up if we are going to support it! If not, happy to pick something else up that you think would be a good first issue :)

[rustyrussell]

I have removed this in #8377 so I'm going to close this now.