fix: stop host teardown from deleting a workdir it never created (#1409)

Host jobs run in a per-job directory under `host.workdir_parent`, which teardown removes. Teardown also deleted `<container.workdir_parent>/<owner>/<repo>`, a path host jobs never create. With an empty parent and no repository that was the filesystem root, and any existing directory at that path was deleted although the job never used it.

This removes that delete instead of guarding it, so teardown only removes what the job created.

---------

Co-authored-by: silverwind <[email protected]>
Reviewed-on: https://gitea.com/gitea/runner/pulls/1409
Reviewed-by: bircni <[email protected]>
Co-authored-by: clintlmartin <[email protected]>

docs/post-task-script.md

@@ -9,13 +9,13 @@ It is configured under `runner.post_task_script` in the runner YAML config (see
 For each task, execution order is:
 
 1. Workflow runs (steps, actions, containers).
-2. In-job cleanup (action `post:` steps, container stop/remove).
+2. In-job cleanup (action `post:` steps, container stop/remove, host job directory removal).
 3. Job outputs are reported to Gitea.
 4. Bind-workdir workspace removal, when `container.bind_workdir` is enabled.
 5. **Post-task script** (this hook).
 6. Final task acknowledgement to Gitea (`reporter.Close()`).
 
-The script is **additive**: it does not replace any built-in cleanup. When `container.bind_workdir` is enabled, the task workspace directory has usually already been deleted before the script starts. `GITEA_WORKSPACE` is still set to the path the job used, for reference.
+The script is **additive**: it does not replace any built-in cleanup. The workspace of host jobs, and of container jobs with `container.bind_workdir`, is deleted before the script starts.
 
 ## Runner stays offline until the script finishes
 
@@ -75,7 +75,7 @@ The script receives `runner.envs` / `runner.env_file` values plus:
 | `GITEA_TASK_ID` | Numeric task ID. |
 | `GITEA_RUN_ID` | Workflow run ID, when provided by the server. |
 | `GITEA_REPOSITORY` | Repository slug (`owner/name`). |
-| `GITEA_WORKSPACE` | Workspace path used for the job (may already be deleted). |
+| `GITEA_WORKSPACE` | Workspace path of the job. |
 | `GITEA_JOB_RESULT` | `success`, `failure`, `cancelled`, `skipped`, or `unknown`. |
 
 The script environment is **not** a full copy of the job container environment. System variables such as `PATH` are only present if you define them in `runner.envs` or `runner.env_file`.