EndpointNotFound deleting volume backend instance

When there is some error in volume creating on booting from volume,
we may get the EndpointNotFound exception when deleting the error instance.
Then we can never delete the instance successfully. The exception should
be ignored.

Change-Id: Ia92b648eb18c70996747d361e227de771f33ee9c
Closes-bug: 1346866
Revert "Deallocate the network if rescheduling for

Revert "Deallocate the network if rescheduling for Ironic"

This reverts commit 963ad71af4750e28745b6de262da11816b403801.

The original fix, targeted towards Nova BM and Ironic tests
is actually making us have more test failures. Lets go
back to the original race... and then we can have a bit
more time to test a proper fix.

Closes-bug #1346424

Change-Id: Icbbe16ffef69132177165d21c727d791b62a232f
Merge "Revert "Deallocate the network if rescheduling for"
Merge "EndpointNotFound deleting volume backend instance"