CLD-5698 - Add e2e smoketests (#23590)

* Prepare: run E2E smoketests with GitHub actions (#23301)
* Port E2E testing scripts from cypress-ui-automation
* Move server to docker-compose, move E2E images to ecrpublic
* Integrate General channel renaming, fixes
* Add local automation-dashboard
 Add readme
* Add E2E smoketests
* Bump postgres to 12
* Fully rely on mattermostdevelopment images

---------

Co-authored-by: Mattermost Build <build@mattermost.com>
Co-authored-by: Saturnino Abril <saturnino.abril@gmail.com>
Co-authored-by: Antonis Stamatiou <stamatiou.antonis@gmail.com>

server/build/gitlab-dc.postgres.yml

@@ -1,7 +1,7 @@
 version: '2.4'
 services:
   postgres:
-    image: ${CI_REGISTRY}/mattermost/ci/images/postgres:10-1
+    image: mattermostdevelopment/mirrored-postgres:12
     restart: always
     environment:
       POSTGRES_USER: mmuser
@@ -12,9 +12,9 @@ services:
      - "./docker/postgres.conf:/etc/postgresql/postgresql.conf"
     healthcheck:
       test: [ "CMD", "pg_isready", "-h", "localhost" ]
-      interval: 5s
-      timeout: 10s
-      retries: 3
+      interval: 10s
+      timeout: 15s
+      retries: 12
     networks:
       default:
         aliases:
@@ -81,7 +81,7 @@ services:
           - grafana
 
   start_dependencies:
-    image: ${CI_REGISTRY}/mattermost/ci/images/mattermost-wait-for-dep:latest-1
+    image: mattermost/mattermost-wait-for-dep:latest
     depends_on:
       - postgres
       - minio
@@ -94,7 +94,6 @@ services:
     networks:
       default:
 
-
 networks:
   default:
     external: