raoachtest/versionupgrade: re-enable schema change step again

Fixes: #58489

Previously, the schema change step inside the version upgrade
test was disabled because of failures. This allowed the test
to become reliable, but we lost coverage of randomized schema
changes in this scenario. To address this, this patch
will re-enable the randomized schema changer workload during
version upgrade, since we have fixed this workload on its
own.

Release note: None

pkg/cmd/roachtest/tests/versionupgrade.go

@@ -116,9 +116,6 @@ func runVersionUpgrade(ctx context.Context, t test.Test, c cluster.Cluster) {
 
 	testFeaturesStep := versionUpgradeTestFeatures.step(c.All())
 	schemaChangeStep := runSchemaChangeWorkloadStep(c.All().RandNode()[0], 10 /* maxOps */, 2 /* concurrency */)
-	// TODO(irfansharif): All schema change instances were commented out while
-	// of #58489 is being addressed.
-	_ = schemaChangeStep
 	backupStep := func(ctx context.Context, t test.Test, u *versionUpgradeTest) {
 		// Verify that backups can be created in various configurations. This is
 		// important to test because changes in system tables might cause backups to
@@ -168,26 +165,26 @@ func runVersionUpgrade(ctx context.Context, t test.Test, c cluster.Cluster) {
 		// as they ought to.
 		binaryUpgradeStep(c.All(), predecessorVersion),
 		testFeaturesStep,
-		// schemaChangeStep,
+		schemaChangeStep,
 		backupStep,
 		// Roll nodes forward, this time allowing them to upgrade, and waiting
 		// for it to happen.
 		binaryUpgradeStep(c.All(), ""),
 		allowAutoUpgradeStep(1),
 		testFeaturesStep,
-		// schemaChangeStep,
+		schemaChangeStep,
 		backupStep,
 		waitForUpgradeStep(c.All()),
 		testFeaturesStep,
-		// schemaChangeStep,
+		schemaChangeStep,
 		backupStep,
 		// Turn tracing on globally to give it a fighting chance at exposing any
 		// crash-inducing incompatibilities or horrendous memory leaks. (It won't
 		// catch most memory leaks since this test doesn't run for too long or does
 		// too much work). Then, run the previous tests again.
 		enableTracingGloballyStep,
 		testFeaturesStep,
-		// schemaChangeStep,
+		schemaChangeStep,
 		backupStep,
 	)