server: fix DRPC option precedence for test-specific settings

Previously, when a test explicitly set TestDRPCDisabled but a global
DRPC override was configured, the global override would incorrectly
take precedence. This meant tests that explicitly disabled DRPC could
still end up running with DRPC enabled.

The fix also adds better logging to indicate when a global override
is being applied, making test behavior more transparent.

Author: shubhamdhama

pkg/base/test_server_args.go

@@ -235,9 +235,12 @@ type SlimTestServerConfig struct {
 type DefaultTestDRPCOption uint8
 
 const (
+	// TestDRPCUnset represents an uninitialized or invalid DRPC option.
+	TestDRPCUnset DefaultTestDRPCOption = iota
+
 	// TestDRPCDisabled disables DRPC; all inter-node connectivity will use gRPC
 	// only.
-	TestDRPCDisabled DefaultTestDRPCOption = iota
+	TestDRPCDisabled
 
 	// TestDRPCEnabled enables DRPC. Some services may still use gRPC if they
 	// have not yet migrated to DRPC.

pkg/testutils/serverutils/test_server_shim.go

@@ -546,8 +546,10 @@ func WaitForTenantCapabilities(
 // `TestServerArgs.Settings` based on that.
 func TryEnableDRPCSetting(ctx context.Context, t TestLogger, args *base.TestServerArgs) {
 	option := args.DefaultDRPCOption
-	if option == base.TestDRPCDisabled && globalDefaultDRPCOptionOverride.isSet {
+	var logSuffix string
+	if option == base.TestDRPCUnset && globalDefaultDRPCOptionOverride.isSet {
 		option = globalDefaultDRPCOptionOverride.value
+		logSuffix = " (override by TestingGlobalDRPCOption)"
 	}
 	enableDRPC := false
 	switch option {
@@ -561,6 +563,7 @@ func TryEnableDRPCSetting(ctx context.Context, t TestLogger, args *base.TestServ
 		return
 	}
 
+	t.Log("DRPC is enabled" + logSuffix)
 	if args.Settings == nil {
 		args.Settings = cluster.MakeClusterSettings()
 	}