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-plugins-combined.yml

@@ -68,8 +68,8 @@ services:
     image: byjg/easy-haproxy:local
     volumes:
       - /var/run/docker.sock:/var/run/docker.sock
-      - ./cloudflare_ips.lst:/etc/haproxy/cloudflare_ips.lst:ro
-      - ./jwt_pubkey.pem:/etc/haproxy/jwt_keys/api_pubkey.pem:ro
+      - ./cloudflare_ips.lst:/etc/easyhaproxy/cloudflare_ips.lst:ro
+      - ./jwt_pubkey.pem:/etc/easyhaproxy/jwt_keys/api_pubkey.pem:ro
     environment:
       EASYHAPROXY_DISCOVER: docker
       HAPROXY_CUSTOMERRORS: "true"
@@ -114,7 +114,7 @@ services:
       easyhaproxy.http.plugin.jwt_validator.algorithm: RS256
       easyhaproxy.http.plugin.jwt_validator.issuer: https://auth.example.com/
       easyhaproxy.http.plugin.jwt_validator.audience: https://api.example.com
-      easyhaproxy.http.plugin.jwt_validator.pubkey_path: /etc/haproxy/jwt_keys/api_pubkey.pem
+      easyhaproxy.http.plugin.jwt_validator.pubkey_path: /etc/easyhaproxy/jwt_keys/api_pubkey.pem
 
       # Block internal/debug endpoints
       easyhaproxy.http.plugin.deny_pages.paths: /internal,/debug,/metrics