Revert "Create compute offering UI: Use big size for form"

Due to some usability issues with the form layout, reverting the
'bigSize' functionality from the createForm.
CLOUDSTACK-4142: listNetworkOfferings API has been changed to not return system owned network offerings to regular user. Therefore, change VPC tier detailView to get services from listNetworks API response instead of listNetworkOfferings API response.
CLOUDSTACK-4142: UI > VPC > tier > detailView > edit action > network offering dropdown > get current network offering from listNetworks API response instead of listNetworkOfferings API response.