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 remove outdated "init" scripts, only keep one in sysvinit, gentoo dir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/settings.json

@@ -0,0 +1,4 @@
+{
+    "go.buildTags": "",
+    "go.testFlags": ["-v"]
+}