Fix row limit not set properly for notebook preview queries (#30105)

* Add repro test

* Fix limit was not properly set for preview queries

e2e/test/scenarios/question/notebook.cy.spec.js

@@ -552,17 +552,35 @@ describe("scenarios > question > notebook", () => {
     });
   });
 
-  it("should properly render previews (metabase#28726)", () => {
+  it("should properly render previews (metabase#28726), (metabase#29959)", () => {
     openOrdersTable({ mode: "notebook" });
     cy.findByTestId("step-data-0-0").within(() => {
       cy.icon("play").click();
+      assertTableRowCount(10);
       cy.findByTextEnsureVisible("Subtotal");
       cy.findByTextEnsureVisible("Tax");
       cy.findByTextEnsureVisible("Total");
+      cy.icon("close").click();
+    });
+
+    cy.button("Row limit").click();
+    cy.findByTestId("step-limit-0-0").within(() => {
+      cy.findByPlaceholderText("Enter a limit").type("5");
+
+      cy.icon("play").click();
+      assertTableRowCount(5);
+
+      cy.findByDisplayValue("5").type("{selectall}50");
+      cy.button("Refresh").click();
+      assertTableRowCount(10);
     });
   });
 });
 
+function assertTableRowCount(expectedCount) {
+  cy.get(".Table-ID:not(.Table-FK)").should("have.length", expectedCount);
+}
+
 function addSimpleCustomColumn(name) {
   enterCustomColumnDetails({ formula: "C" });
   cy.findByText("ategory").click();

frontend/src/metabase/query_builder/components/notebook/NotebookStepPreview.jsx

@@ -38,8 +38,9 @@ class NotebookStepPreview extends React.Component {
 
   getPreviewQuestion(step) {
     const query = step.previewQuery;
+    const hasSuitableLimit = query.hasLimit() && query.limit() < 10;
     return Question.create()
-      .setQuery(query.limit() < 10 ? query : query.updateLimit(10))
+      .setQuery(hasSuitableLimit ? query : query.updateLimit(10))
       .setDisplay("table")
       .setSettings({ "table.pivot": false });
   }