Note: this is a squash of two changes since they are
dependent on each other, and are currently blocking
the gate queue.
Sometimes cleanup methods are failing in the check and
gate queues trying to delete non-existing namespaces.
Since they could have been deleted asynchronously, don't
raise if the failure is "No such file or directory" since
the system is in the intended state.
Cleaned-up the DHCP agent to longer check for existence
first, and the tests to longer mock-out the namespace
exists check.
Fix test_legacy_router_lifecycle failures
Multi-path routes returned via the pyroute2 library have
their outgoing interfaces in the 'multipath' dictionary
element, not in the route dictionary. In that case return
all the multipath routes correctly.
Change-Id: I5415cb3a88ff2640a19598a1fcb2278388815343
Closes-bug: #1795482
Closes-bug: #1795548
7e90c5fb73