(core) Use different user in ActionLog tests

Summary:
Nearby deployment tests used the same user, which was
causing the full suite to fail. Repeated logins with a second
verification step (TOTP) fail in Cognito if the same verification code
is used twice. This happened to be the case since the gap
between tests wasn't long enough for a new code to be generated.

Test Plan: Manually verified deployment tests now pass.

Reviewers: jarek

Reviewed By: jarek

Differential Revision: https://phab.getgrist.com/D3414

test/nbrowser/ActionLog.ts

@@ -24,7 +24,7 @@ describe('ActionLog', function() {
   }
 
   before(async function() {
-    const session = await gu.session().user('user4').login();
+    const session = await gu.session().user('user1').login();
     await session.tempDoc(cleanup, 'Hello.grist');
     await gu.dismissWelcomeTourIfNeeded();
   });

test/nbrowser/homeUtil.ts

@@ -179,9 +179,13 @@ export class HomeUtil {
     const code = authenticator.generate(secret);
     await this.driver.find('input[name="verificationCode"]').sendKeys(code);
     await this.driver.find('.test-mfa-submit').click();
-    await this.driver.wait(async () => {
-      return !await this.driver.findContent('.test-mfa-title', 'Almost there!').isPresent();
-    }, 4000);
+    await this.driver.wait(
+      async () => {
+        return !await this.driver.findContent('.test-mfa-title', 'Almost there!').isPresent();
+      },
+      4000,
+      'Possible reason: verification code is invalid or expired (i.e. was recently used to log in)'
+    );
   }
 
   /**