This reverts commit 9c3c19f07c.
Following the merge of Ie98d5e3760cdb17450aea546f4b61f5ba14baf1c, the
creation of new router uses RouterL3AgentBinding and its' new
binding_index attribute to ensure correctness of the resources. As such,
the ALLOCATING state (which was used to do just that) is no longer
needed and can be removed.
Closes-Bug: #1609738
Change-Id: Ib04e08df13ef4e6b94bd588854a5795163e2a617