Improve time to run cluster application specs

This reduces the time to run the spec/models/clusters/applications/* by
40 seconds (200 => 160 seconds) on my computer.

spec/support/shared_examples/models/cluster_application_status_shared_examples.rb

@@ -264,6 +264,8 @@ RSpec.shared_examples 'cluster application status specs' do |application_name|
   describe '#available?' do
     using RSpec::Parameterized::TableSyntax
 
+    let_it_be(:cluster) { create(:cluster, :provided_by_gcp) }
+
     where(:trait, :available) do
       :not_installable   | false
       :installable       | false
@@ -280,7 +282,7 @@ RSpec.shared_examples 'cluster application status specs' do |application_name|
     end
 
     with_them do
-      subject { build(application_name, trait) }
+      subject { build(application_name, trait, cluster: cluster) }
 
       if params[:available]
         it { is_expected.to be_available }

spec/support/shared_examples/models/cluster_application_version_shared_examples.rb

@@ -2,16 +2,18 @@
 
 RSpec.shared_examples 'cluster application version specs' do |application_name|
   describe 'update_available?' do
+    let_it_be(:cluster) { create(:cluster, :provided_by_gcp) }
+
     let(:version) { '0.0.0' }
 
-    subject { create(application_name, :installed, version: version).update_available? }
+    subject { build(application_name, :installed, version: version, cluster: cluster).update_available? }
 
     context 'version is not the same as VERSION' do
       it { is_expected.to be_truthy }
     end
 
     context 'version is the same as VERSION' do
-      let(:application) { build(application_name) }
+      let(:application) { build(application_name, cluster: cluster) }
       let(:version) { application.class.const_get(:VERSION, false) }
 
       it { is_expected.to be_falsey }