sql: use descs.Txn for schemachanger.txn

This commit is to use the new internal executor interface introduced by cockroachdb#93218
for `schemachanger.txn()`.

informs cockroachdb#91004
Release Note: None

pkg/ccl/backupccl/restore_job.go

@@ -1917,8 +1917,8 @@ func revalidateIndexes(
 	// We don't actually need the 'historical' read the way the schema change does
 	// since our table is offline.
 	runner := descs.NewHistoricalInternalExecTxnRunner(hlc.Timestamp{}, func(ctx context.Context, fn descs.InternalExecFn) error {
-		return execCfg.InternalDB.Txn(ctx, func(ctx context.Context, txn isql.Txn) error {
-			return fn(ctx, txn, descs.FromTxn(txn))
+		return execCfg.InternalDB.DescsTxn(ctx, func(ctx context.Context, txn descs.Txn) error {
+			return fn(ctx, txn)
 		})
 	})
 

pkg/jobs/registry.go

@@ -111,8 +111,8 @@ type Registry struct {
 	adoptionCh  chan adoptionNotice
 	sqlInstance sqlliveness.Instance
 
-	// sessionBoundInternalExecutorFactory provides a way for jobs to create
-	// internal executors. This is rarely needed, and usually job resumers should
+	// internalDB provides a way for jobs to create internal executors.
+	// This is rarely needed, and usually job resumers should
 	// use the internal executor from the JobExecCtx. The intended user of this
 	// interface is the schema change job resumer, which needs to set the
 	// tableCollectionModifier on the internal executor to different values in

pkg/sql/alter_table.go

@@ -545,7 +545,7 @@ func (n *alterTableNode) startExec(params runParams) error {
 				ck.CheckDesc().Validity = descpb.ConstraintValidity_Validated
 			} else if fk := c.AsForeignKey(); fk != nil {
 				if err := validateFkInTxn(
-					params.ctx, params.p.InternalSQLTxn(), params.p.descCollection, n.tableDesc, name,
+					params.ctx, params.p.InternalSQLTxn(), n.tableDesc, name,
 				); err != nil {
 					return err
 				}