sql: don't distribute migration queries

This patch inhibits DistSQL distribution for the queries that the
migrations run. This was prompted by #44101, which is causing a
distributed query done soon after a node startup to sometimes fail.

I've considered more bluntly disabling distribution for any query for a
short period of time after the node starts up, but I went with the more
targeted change to migrations because I think it's a bad idea for
migrations to use query distribution even outside of #44101 -
distributed queries are more fragile than local execution in general
(for example, because of DistSender retries). And migrations can't
tolerate any flakiness.

Fixes #43957
Fixes #44005
Touches #44101

Release note: None

pkg/cmd/roachtest/acceptance.go

@@ -46,7 +46,6 @@ func registerAcceptance(r *testRegistry) {
 		{name: "status-server", fn: runStatusServer},
 		{
 			name: "version-upgrade",
-			skip: "#43957",
 			fn:   runVersionUpgrade,
 			// This test doesn't like running on old versions because it upgrades to
 			// the latest released version and then it tries to "head", where head is

pkg/server/server.go

@@ -1599,10 +1599,23 @@ func (s *Server) Start(ctx context.Context) error {
 	if migrationManagerTestingKnobs := s.cfg.TestingKnobs.SQLMigrationManager; migrationManagerTestingKnobs != nil {
 		mmKnobs = *migrationManagerTestingKnobs.(*sqlmigrations.MigrationManagerTestingKnobs)
 	}
+	migrationsExecutor := sql.MakeInternalExecutor(
+		ctx, s.pgServer.SQLServer, s.internalMemMetrics, s.ClusterSettings())
+	migrationsExecutor.SetSessionData(
+		&sessiondata.SessionData{
+			// Migrations need an executor with query distribution turned off. This is
+			// because the node crashes if migrations fail to execute, and query
+			// distribution introduces more moving parts. Local execution is more
+			// robust; for example, the DistSender has retries if it can't connect to
+			// another node, but DistSQL doesn't. Also see #44101 for why DistSQL is
+			// particularly fragile immediately after a node is started (i.e. the
+			// present situation).
+			DistSQLMode: sessiondata.DistSQLOff,
+		})
 	migMgr := sqlmigrations.NewManager(
 		s.stopper,
 		s.db,
-		s.internalExecutor,
+		&migrationsExecutor,
 		s.clock,
 		mmKnobs,
 		s.NodeID().String(),