Fix engine connection break when starting onboarding from a fresh install (#4263)

* Make electron test setting overrides not entirely replace default settings

* Add failing test

* Fix test by checking for healthy engine connection before executing demo code

* Fix one electron test that assumed all settings got wiped if you override any.

* 🤷🏻‍♂️ an engine-side camera position in one of the E2E tests changed by 0.01 randomly

e2e/playwright/testing-gizmo.spec.ts

@@ -292,7 +292,7 @@ test.describe(`Testing gizmo, fixture-based`, () => {
     await test.step(`Verify the camera moved`, async () => {
       await scene.expectState({
         camera: {
-          position: [0, -23865.37, 11073.54],
+          position: [0, -23865.37, 11073.53],
           target: [0, 0, 0],
         },
       })