Blender Git Loki

Fix T89415: update multi input indices after deleting a node

When deleting a node, links attached to that node are deleted, but if one
of those links was connected to a multi input socket, the indices of the
other links connected to it were not updated. This adds updates both in
the case of a normal delete as well as after a delete with reconnect.

Differential Revision: https://developer.blender.org/D11716