sql: fix makeFixedTimestampInternalExecRunner to use correct Internal…

… Executor

This is part of the effort to deprecate `ieFactory.NewInternalExecutor()`.
The internal executor should be bound to the outer txn, if there's one.

Release note: None

pkg/sql/backfill.go

@@ -173,12 +173,10 @@ func (sc *SchemaChanger) makeFixedTimestampInternalExecRunner(
 	readAsOf hlc.Timestamp,
 ) descs.HistoricalInternalExecTxnRunner {
 	return descs.NewHistoricalInternalExecTxnRunner(readAsOf, func(ctx context.Context, retryable descs.InternalExecFn) error {
-		return sc.fixedTimestampTxn(ctx, readAsOf, func(
-			ctx context.Context, txn *kv.Txn, descriptors *descs.Collection,
+		return sc.fixedTimestampTxnWithExecutor(ctx, readAsOf, func(
+			ctx context.Context, txn *kv.Txn, _ *sessiondata.SessionData, descriptors *descs.Collection, ie sqlutil.InternalExecutor,
 		) error {
-			// We need to re-create the evalCtx since the txn may retry.
-			ie := sc.ieFactory.NewInternalExecutor(NewFakeSessionData(sc.execCfg.SV()))
-			return retryable(ctx, txn, ie, nil /* descriptors */)
+			return retryable(ctx, txn, ie, descriptors)
 		})
 	})
 }