fix(test): use ROLE_FILE_VARS_MAIN constant instead of hard-coded vars path

test_file_spot flags hard-coded role-file paths; import the SPOT constant from
utils.roles.mapping and build the path from it.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

tests/lint/ansible/roles/test_no_leaky_proxy_role_vars.py

@@ -28,6 +28,7 @@ from typing import TYPE_CHECKING
 
 from utils.annotations.message import in_github_actions, warning
 from utils.cache.files import read_text
+from utils.roles.mapping import ROLE_FILE_VARS_MAIN
 
 from . import PROJECT_ROOT
 
@@ -63,7 +64,7 @@ def _collect_findings(root: Path) -> list[LeakyVarFinding]:
     for role_dir in sorted(roles_dir.iterdir()):
         if not role_dir.is_dir():
             continue
-        vars_path = role_dir / "vars" / "main.yml"
+        vars_path = role_dir / ROLE_FILE_VARS_MAIN
         if not vars_path.is_file():
             continue
         try: