Make unit test floating ips bulk faster

The unit test is only used to test whether the code branch is
executed with pre-defined logic, so it does make sense to create
as less as dataset if we can achieve that goal.

Currently the unit test for floating ip bulk operation in nova
create a rather a big data set to run the test. This patch adjust
it with smaller one.

the results shows (ignore the first one because env setup)
                                                   [former] [current]
test_create_bad_cidr_fail                       OK  4.27     8.30
test_create_duplicate_fail                      OK  8.01     1.20
test_create_invalid_cidr_fail                   OK  0.10     0.14
test_create_ips                                 OK  0.77     0.18
test_create_ips_pool                            OK  7.65     0.17
test_delete_ips                                 OK  10.01    0.35
test_list_ip_by_host                            OK  0.14     0.27
test_list_ips                                   OK  0.15     0.25

Change-Id: I2ee5b5186f0c88b80ed20a0dbc16af9360e28332
VMware: remove ESX support for getting resource pool

The ESX driver is no longer supported. We should only return the
resource pool for the cluster.

In order to test this the patch had to update the test_vmops to
ensure that a cluster was used.

The patch also drops the method get_mo_id_from_instance which is
no longer used.

Change-Id: I9d99a5be58ef5a2a7d41dfd488ac24f38d2c79d3
Merge "Make unit test floating ips bulk faster"
Merge "VMware: remove ESX support for getting resource pool"