core: fixing build break

VdcActionType.ImportProviderCertificate was added in change Ic9adb2 but
the command wasn't added causing the VdcActionType test to fail -
commenting the use and removing the enum value at the moment.

Change-Id: I1e8d48344f30085fac8a6d5d4c4c2c15da987246
Signed-off-by: Liron Aravot <laravot@redhat.com>