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/conftest.py

@@ -0,0 +1,43 @@
+"""
+Pytest configuration and fixtures for EasyHAProxy tests.
+
+This module provides session-wide and function-level fixtures for testing.
+"""
+
+import os
+import shutil
+import tempfile
+import pytest
+
+
+# Create a session-wide temporary directory for all tests
+# Use a different prefix to avoid conflicts with cleanup plugin (which looks for "easyhaproxy_*")
+_test_session_dir = tempfile.mkdtemp(prefix="pytest_easyhaproxy_")
+os.environ["EASYHAPROXY_BASE_PATH"] = _test_session_dir
+
+
+@pytest.fixture(scope="function", autouse=True)
+def reset_consts():
+    """
+    Reset Consts before and after each test.
+
+    This ensures:
+    1. Each test picks up the EASYHAPROXY_BASE_PATH environment variable
+    2. Tests don't get permission errors trying to write to /etc/easyhaproxy/
+    3. Consts path cache is cleared between tests for isolation
+    """
+    from functions import Consts
+    Consts.reset()
+    yield
+    Consts.reset()
+
+
+def pytest_sessionfinish(session, exitstatus):
+    """
+    Cleanup session temporary directory after all tests complete.
+    """
+    try:
+        shutil.rmtree(_test_session_dir)
+    except Exception:
+        # Ignore cleanup errors
+        pass