test: test offline runner registration (#1449)

Reviewed-on: https://code.forgejo.org/forgejo/end-to-end/pulls/1449
Reviewed-by: Mathieu Fenniak <mfenniak@noreply.code.forgejo.org>
Co-authored-by: Andreas Ahlenstorf <andreas@ahlenstorf.ch>
Co-committed-by: Andreas Ahlenstorf <andreas@ahlenstorf.ch>

actions/example-create-runner-file/runner-config.yaml

@@ -0,0 +1,31 @@
+
+log:
+  level: debug
+
+runner:
+  file: .runner
+  capacity: 1
+  env_file: .env
+  timeout: 3h
+  insecure: false
+  fetch_timeout: 5s
+  fetch_interval: 2s
+  labels:
+    - "create-runner-file:docker://code.forgejo.org/oci/node:24-trixie"
+
+cache:
+  enabled: true
+  dir: "/srv/example/cache"
+  host: ""
+  port: 0
+
+container:
+  network: "bridge"
+  privileged: false
+  options:
+  workdir_parent:
+  valid_volumes: ["/srv/example"]
+  docker_host: ""
+
+host:
+  workdir_parent: