Bluetooth: Mesh: Fixes Relay to frnd_cred message

If low power node publish with unicast address other
than friend address, the friend node should relayed
this message to all network interface.

When Proxy feature enabled, message from gatt bearer should
relay to adv bearer even relay feature disabled.

Fixes: #29544

Signed-off-by: Lingao Meng <mengabc1086@gmail.com>