Remove unused network_api.get_floating_ips_by_fixed_address()

Last usage was removed in 61e5b8e7da3b36db9a09f80d62ebf2e276bbe88b

Change-Id: I55626e7174b2380369b80fbced15093c2105aec1
Remove unused network_api.get_instance_uuids_by_ip_filter()

Last usage was removed in ae781ee97947c33d6d43e4c21df4f338c875bf1c

Change-Id: I33dc14085ca0c887778c7379f0498714e8d30425