chore: clean up "contrib" dir (#37690)

1. remove useless files like "backport.go", "update_dependencies.sh"
2. remove outdated "init" scripts, only keep one in sysvinit, gentoo dir
is also kept because it still uses openrc
3. move "service" related config and scripts into "service" directory

contrib/development/vscode/launch.json

@@ -0,0 +1,18 @@
+{
+  "version": "0.2.0",
+  "configurations": [
+    {
+      "name": "Launch",
+      "type": "go",
+      "request": "launch",
+      "mode": "debug",
+      "buildFlags": "",
+      "program": "${workspaceRoot}/main.go",
+      "env": {
+        "GITEA_WORK_DIR": "${workspaceRoot}",
+      },
+      "args": ["web"],
+      "showLog": true
+    }
+  ]
+}