CI: Set slow_chown for overlayfs snapshotter

Userns requires idmap mounts or to opt-in for a slow and expensive
chown. As idmap mounts support for overlayfs was merged in 5.19, let's
add the slow_chown config for our CI.

The config is harmless to keep it in new kernels, as if idmap mounts is
supported, it will be just used. Whenever all our CI is run with kernels
>= 5.19, we can remove this setting.

Signed-off-by: Rodrigo Campos <[email protected]>

Author: rata

script/test/utils.sh

@@ -52,6 +52,13 @@ version=2
 
 [plugins."io.containerd.grpc.v1.cri"]
   drain_exec_sync_io_timeout = "10s"
+
+# Userns requires idmap mount support for overlayfs (added in 5.19)
+# Let's opt-in for a recursive chown, so we can always test this even in old distros.
+# Note that if idmap mounts support is present, we will use that, so it is harmless to keep this
+# here.
+[plugins."io.containerd.snapshotter.v1.overlayfs"]
+    slow_chown = true
 EOF
 
   if command -v sestatus >/dev/null 2>&1; then