Visual tests for static-viz (via _internal) (#17561)

frontend/test/metabase-visual/internal/static-viz.cy.spec.js

+import { restore } from "__support__/e2e/cypress";
+
+describe("visual tests > internal > static-viz", () => {
+  beforeEach(() => {
+    restore();
+    cy.signInAsNormalUser();
+  });
+
+  it("basic charts", () => {
+    cy.visit("/_internal/static-viz");
+
+    cy.findByText("Bar chart with timeseries data");
+    cy.findByText("Line chart with timeseries data");
+    cy.findByText("Donut chart showing categorical data");
+
+    cy.percySnapshot();
+  });
+});