Add stubbing Prometheus requests from UsageData

spec/lib/generators/gitlab/usage_metric_definition/redis_hll_generator_spec.rb

@@ -12,6 +12,20 @@ RSpec.describe Gitlab::UsageMetricDefinition::RedisHllGenerator do
   # See https://github.com/rspec/rspec-mocks/issues/1079
   before do
     stub_const("#{Gitlab::UsageMetricDefinitionGenerator}::TOP_LEVEL_DIR", temp_dir)
+    # Stub Prometheus requests from Gitlab::Utils::UsageData
+    stub_request(:get, %r{^http[s]?://::1:9090/-/ready})
+      .to_return(
+        status: 200,
+        body: [{}].to_json,
+        headers: { 'Content-Type' => 'application/json' }
+      )
+
+    stub_request(:get, %r{^http[s]?://::1:9090/api/v1/query\?query=.*})
+      .to_return(
+        status: 200,
+        body: [{}].to_json,
+        headers: { 'Content-Type' => 'application/json' }
+      )
   end
 
   it 'creates metric definition files' do