🔧 Add general improvements to integration tests

This commit marks as skip (temporal) several flaky/randomly-failing
tests.

It also moves the integration test execution from circleci to github
actions.

frontend/playwright/ui/specs/design-tab.spec.js

@@ -90,7 +90,8 @@ test.describe("Shape attributes", () => {
     await expect(workspace.page.getByTestId("add-fill")).toBeDisabled();
   });
 
-  test("Cannot add a new text fill when the limit has been reached", async ({
+  // FIXME: flaky
+  test.skip("Cannot add a new text fill when the limit has been reached", async ({
     page,
   }) => {
     const workspace = new WorkspacePage(page);