Revert Cypress upgrade (v5.3.0. -> v3.8.2) (#13398)

* Revert Cypress upgrade (v5.3.0. -> v3.8.2)

Additionally needed to make all tests pass:
* Fix Cypress flakes (cannot find "Not now" string within a modal)

frontend/test/metabase/scenarios/question/notebook.cy.spec.js

@@ -226,9 +226,7 @@ describe("scenarios > question > notebook", () => {
         typeAndBlurUsingLabel("Name", "Q3");
         cy.findByText("Save").click();
       });
-      modal().within(() => {
-        cy.findByText("Not now").click();
-      });
+      cy.findByText("Not now").click();
 
       cy.log("**Assert that the Q3 is in 'Our analytics'**");
 
@@ -278,9 +276,7 @@ describe("scenarios > question > notebook", () => {
         cy.findByText("Save").click();
       });
 
-      modal().within(() => {
-        cy.findByText("Not now").click();
-      });
+      cy.findByText("Not now").click();
 
       cy.get(".Icon-notebook").click();
 

package.json

@@ -116,7 +116,7 @@
     "color-diff": "^1.1.0",
     "concurrently": "^3.1.0",
     "css-loader": "^0.28.7",
-    "cypress": "^5.3.0",
+    "cypress": "3.8.2",
     "documentation": "^4.0.0-rc.1",
     "enzyme": "^3.8.0",
     "enzyme-2": "npm:enzyme@2",
@@ -224,6 +224,6 @@
     ]
   },
   "resolutions": {
-    "cypress": "5.3.0"
+    "cypress": "3.8.2"
   }
 }