prow: increase the number of alias ip for network test (#659)
prow: increase the number of alias ip for network test (#659)

There are less IPs compared to the number of network tests being run in
parallel.
Increate the number of IPs and fix the following errors:
Code: IP_IN_USE_BY_ANOTHER_RESOURCE, Message: IP '10.128.3.140/31' is already being used by another resource.
zmarano/compute-image-tools,GoogleCloudPlatform/compute-daisy,GoogleCloudPlatform/compute-image-import,GoogleCloudPlatform/compute-image-import,GoogleCloudPlatform/compute-daisy,GoogleCloudPlatform/compute-image-import,zmarano/compute-image-tools,zmarano/compute-image-tools,adjackura/compute-image-tools,GoogleCloudPlatform/compute-image-tools,GoogleCloudPlatform/compute-image-tools,adjackura/compute-image-tools,adjackura/compute-image-tools,GoogleCloudPlatform/compute-image-tools