CLD-7841 Optimize E2E testing costs (#27883)

* Utilize free runners for E2E tests, report back to PR on run completion
* Increase test stability on smaller instances
* Merge worker reports
* merge start+prepare steps
* upgrade keycloak
* increase test timeouts
* Add video recording to report artifacts

Co-authored-by: Saturnino Abril <5334504+saturninoabril@users.noreply.github.com>

---------

Co-authored-by: Saturnino Abril <5334504+saturninoabril@users.noreply.github.com>

e2e-tests/cypress/tests/integration/channels/notifications/at_mentions_spec.js

@@ -41,6 +41,10 @@ describe('Notifications', () => {
             // # Login as receiver and visit off-topic channel
             cy.apiLogin(receiver);
             cy.visit(`/${testTeam.name}/channels/${testChannel.name}`);
+
+            // # Wait for the page to fully load before continuing
+            cy.get('#channelHeaderDropdownButton').should('be.visible').and('have.text', testChannel.display_name);
+
             cy.get(`#sidebarItem_${otherChannel.name}`).click();
             cy.get('#sidebarItem_off-topic').click();
         });
@@ -284,4 +288,5 @@ function setNotificationSettings(desiredSettings = {first: true, username: true,
 
     // # Navigate to a channel we are NOT going to post to
     cy.get(`#sidebarItem_${channelName}`).scrollIntoView().click({force: true});
+    cy.get('#loadingSpinner').should('not.exist');
 }