make vm_count in google_compute_resource_policy as optional (#6694)
make vm_count in google_compute_resource_policy as optional (#6694)

Co-authored-by: Timofey Yushchenko <a9b680a295fe15cecd3a64254e104102fe7b2fb5@google.com>
GoogleCloudPlatform/magic-modules,GoogleCloudPlatform/magic-modules,GoogleCloudPlatform/magic-modules,GoogleCloudPlatform/magic-modules,GoogleCloudPlatform/magic-modules