Migrate configuration paths to /etc/easyhaproxy and improve health check support in E2E tests

- Refactored HAProxy configuration files, templates, and paths to use `/etc/easyhaproxy` instead of `/etc/haproxy`.
- Updated Dockerfile to generate DH params and placeholder certificates in the new configuration directory.
- Added health check support with timeout to `DockerComposeFixture` in E2E test utilities.
- Adjusted tests, templates, and plugins to use the new `Consts`-based configuration paths.
- Introduced pytest fixtures for environment isolation and temporary directory management.

tests_e2e/docker/docker-compose-portainer.yml

@@ -62,8 +62,8 @@ services:
     image: byjg/easy-haproxy:5.0.0
     volumes:
       - /var/run/docker.sock:/var/run/docker.sock
-      - certs_certbot:/certs/certbot
-#      - certs_haproxy:/certs/haproxy
+      - certs_certbot:/etc/easyhaproxy/certs/certbot
+#      - certs_haproxy:/etc/easyhaproxy/certs/haproxy
 
     environment:
       EASYHAPROXY_DISCOVER: docker