Removing flaky flag on issue 19889 e2e test (#38791)

The `19889-native-query-export-column-order.cy.spec.js` test hasn't flaked in over 30 days per [replay.io](https://app.replay.io/team/dzoyNTM4ZjRmOC05YmFlLTRiYjYtYjljYi1jOGYzOWUyMjRhZWY=/tests/dHJ0OjEyMDIwNjkzMWYyMDExMmUzZmMxNDE0MmMxMWFiY2I3NjlmZTliNDE=?param=dzoyNTM4ZjRmOC05YmFlLTRiYjYtYjljYi1jOGYzOWUyMjRhZWY%3D&param=tests&param=dHJ0OjEyMDIwNjkzMWYyMDExMmUzZmMxNDE0MmMxMWFiY2I3NjlmZTliNDE%3D) and I can't make it fail locally after several repeated attempts.

At this point I'm just removing the flaky flag and closing until we can get it to flake again.

Fixes #36682

e2e/test/scenarios/sharing/downloads/reproductions/19889-native-query-export-column-order.cy.spec.js

@@ -9,7 +9,7 @@ const questionDetails = {
 
 const testCases = ["csv", "xlsx"];
 
-describe("issue 19889", { tags: "@flaky" }, () => {
+describe("issue 19889", () => {
   beforeEach(() => {
     cy.intercept("POST", "/api/dataset").as("dataset");