ipaddress: IPv6Address.reverse_pointer produces an invalid name for an address with a scope id

Bug report

Since gh-88178 (a2104b7ce), :attr:~ipaddress.IPv6Address.exploded includes
the %scope_id suffix. IPv6Address._reverse_pointer derives the pointer
from self.exploded and only strips :, so the scope id is reversed into
the name:

>>> import ipaddress
>>> ipaddress.IPv6Address('fe80::1%eth0').reverse_pointer
'0.h.t.e.%.1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.8.e.f.ip6.arpa'

A scope id is link-local and is not part of the address, so it must not appear
in the reverse DNS name. The correct value is the one for fe80::1:

>>> ipaddress.IPv6Address('fe80::1').reverse_pointer
'1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.8.e.f.ip6.arpa'

Before a2104b7ce this raised :exc:~ipaddress.AddressValueError; it now returns
a malformed name silently.

Linked PRs

• gh-155837

Start at ipaddress.IPv6Address._reverse_pointer and the reverse_pointer examples in this report. Check how the scope_id suffix enters IPv6Address.exploded and verify the reverse DNS name for fe80::1%eth0 matches the unsuffixed address. Done means the scope identifier is absent from the generated pointer and the prior malformed output is covered by a regression test.