Remove the kDNSServiceInterfaceIndexLocalOnly special-case on Darwin.

Interface kDNSServiceInterfaceIndexLocalOnly means the _registration_ is
local-only, not that the registered host is localhost and has a loopback
address.  There can be local-only registrations for other hosts, and we need to
do actual address resolution.

src/platform/Darwin/DnssdContexts.cpp

@@ -431,18 +431,6 @@ CHIP_ERROR ResolveContext::OnNewAddress(uint32_t interfaceId, const struct socka
  return CHIP_NO_ERROR;
 }
 
-CHIP_ERROR ResolveContext::OnNewLocalOnlyAddress()
-{
- sockaddr_in6 sockaddr;
- memset(&sockaddr, 0, sizeof(sockaddr));
- sockaddr.sin6_len = sizeof(sockaddr);
- sockaddr.sin6_family = AF_INET6;
- sockaddr.sin6_addr = in6addr_loopback;
- sockaddr.sin6_port = htons((unsigned short) interfaces[kDNSServiceInterfaceIndexLocalOnly].service.mPort);
-
- return OnNewAddress(kDNSServiceInterfaceIndexLocalOnly, reinterpret_cast<struct sockaddr *>(&sockaddr));
-}
-
 bool ResolveContext::HasAddress()
 {
  for (auto & interface : interfaces)

src/platform/Darwin/DnssdImpl.cpp

@@ -328,12 +328,6 @@ static void OnResolve(DNSServiceRef sdRef, DNSServiceFlags flags, uint32_t inter
  if (kDNSServiceErr_NoError == err)
  {
  sdCtx->OnNewInterface(interfaceId, fullname, hostname, port, txtLen, txtRecord);
- if (kDNSServiceInterfaceIndexLocalOnly == interfaceId)
- {
- sdCtx->OnNewLocalOnlyAddress();
- sdCtx->Finalize();
- return;
- }
  }
 
  if (!(flags & kDNSServiceFlagsMoreComing))

src/platform/Darwin/DnssdImpl.h

@@ -204,7 +204,6 @@ struct ResolveContext : public GenericContext
  void DispatchSuccess() override;
 
  CHIP_ERROR OnNewAddress(uint32_t interfaceId, const struct sockaddr * address);
- CHIP_ERROR OnNewLocalOnlyAddress();
  bool HasAddress();
 
  void OnNewInterface(uint32_t interfaceId, const char * fullname, const char * hostname, uint16_t port, uint16_t txtLen,