KVM: selftests: Remove duplicate LAUNCH_UPDATE_VMSA call in SEV-ES migrate test

KVM: selftests: Remove duplicate LAUNCH_UPDATE_VMSA call in SEV-ES migrate test

Drop the explicit KVM_SEV_LAUNCH_UPDATE_VMSA call when creating an SEV-ES
VM in the SEV migration test, as sev_vm_create() automatically updates the
VMSA pages for SEV-ES guests.  The only reason the duplicate call doesn't
cause visible problems is because the test doesn't actually try to run the
vCPUs.  That will change when KVM adds a check to prevent userspace from
re-launching a VMSA (which corrupts the VMSA page due to KVM writing
encrypted private memory).

Fixes: 69f8e15ab61f ("KVM: selftests: Use the SEV library APIs in the intra-host migration test")
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260310234829.2608037-2-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>