Ports 51 tests from norace_1_test.go and 24 tests from norace_2_test.go
as [SkippableFact] integration tests. Creates test harness infrastructure
(IntegrationTestBase, CheckHelper, NatsTestClient, TestServerHelper,
TestCluster) and tags all tests with [Trait("Category", "NoRace")].
Tests skip unless NATS_INTEGRATION_ENABLED=true is set.
