fix(terraform): Improved bad performance pathlib check (#5939)

Made check for  first to avoid heavy pathlib calculations

Author: bo156

checkov/terraform/tf_parser.py

@@ -525,9 +525,10 @@ def add_tfvars_with_source_dir(self, module: Module, source: str, source_dir: st
         if not self.external_variables_data:
             return
         for var_name, default, path in self.external_variables_data:
-            if Path(source_dir) in Path(path).parents and ".tfvars" in path:
-                block = [{var_name: {"default": default}}]
-                module.add_blocks(BlockType.TF_VARIABLE, block, path, source)
+            if ".tfvars" in path:
+                if Path(source_dir) in Path(path).parents:
+                    block = [{var_name: {"default": default}}]
+                    module.add_blocks(BlockType.TF_VARIABLE, block, path, source)
 
     def get_dirname(self, path: TFDefinitionKey) -> str:
         file_path = path.file_path