Fix metric/ci_mixin_spec using kubevirt vm

The metric/ci_mixin_spec was using a kubeivrt vm as an example of a
class which doesn't support capture.

This is no longer accurate as we have added C&U support for kubevirt,
plus we shouldn't be using provider plugin classes in core.

These specs are essentially testing that a class that includes a module
with `supports :capture` responds to `.supports?(:capture)` with true
which isn't actually testing anything.

spec/models/metric/ci_mixin_spec.rb

@@ -1,4 +1,6 @@
 RSpec.describe Metric::CiMixin do
+  include Spec::Support::SupportsHelper
+
   context "with a Vm" do
     let(:vm) { FactoryBot.create(:vm_vmware) }
 
@@ -63,26 +65,4 @@
       end
     end
   end
-
-  context "#supports?(:capture)" do
-    context "with a VM" do
-      let(:unsupported_vm) { FactoryBot.create(:vm_kubevirt) }
-      let(:supported_vm)   { FactoryBot.create(:vm_vmware) }
-
-      it "correctly checks capture support" do
-        expect(unsupported_vm.supports?(:capture)).to be_falsy
-        expect(supported_vm.supports?(:capture)).to be_truthy
-      end
-    end
-
-    context "with a Host" do
-      let(:unsupported_host) { FactoryBot.create(:ibm_power_hmc_host) }
-      let(:supported_host)   { FactoryBot.create(:host_vmware) }
-
-      it "correctly checks capture support" do
-        expect(unsupported_host.supports?(:capture)).to be_falsy
-        expect(supported_host.supports?(:capture)).to be_truthy
-      end
-    end
-  end
 end