[SIEM] Improves navigation Cypress tests time execution (elastic#54273)

* extracts before

* fixes the type check failure

x-pack/legacy/plugins/siem/cypress/integration/smoke_tests/navigation/navigation.spec.ts

@@ -4,7 +4,7 @@
  * you may not use this file except in compliance with the Elastic License.
  */
 
-import { OVERVIEW_PAGE, TIMELINES_PAGE } from '../../lib/urls';
+import { TIMELINES_PAGE } from '../../lib/urls';
 import {
   NAVIGATION_HOSTS,
   NAVIGATION_NETWORK,
@@ -14,33 +14,27 @@ import {
 import { loginAndWaitForPage } from '../../lib/util/helpers';
 
 describe('top-level navigation common to all pages in the SIEM app', () => {
-  it('navigates to the Overview page', () => {
+  before(() => {
     loginAndWaitForPage(TIMELINES_PAGE);
-
+  });
+  it('navigates to the Overview page', () => {
     cy.get(NAVIGATION_OVERVIEW).click({ force: true });
-
     cy.url().should('include', '/siem#/overview');
   });
 
   it('navigates to the Hosts page', () => {
-    loginAndWaitForPage(TIMELINES_PAGE);
-
     cy.get(NAVIGATION_HOSTS).click({ force: true });
 
     cy.url().should('include', '/siem#/hosts');
   });
 
   it('navigates to the Network page', () => {
-    loginAndWaitForPage(TIMELINES_PAGE);
-
     cy.get(NAVIGATION_NETWORK).click({ force: true });
 
     cy.url().should('include', '/siem#/network');
   });
 
   it('navigates to the Timelines page', () => {
-    loginAndWaitForPage(OVERVIEW_PAGE);
-
     cy.get(NAVIGATION_TIMELINES).click({ force: true });
 
     cy.url().should('include', '/siem#/timelines');