`NewCRIService()` may easily fail and its error has to be ignored
unless the CRI plugin is in the `required_plugins` list.
Now this has to be called before `RegisterReadiness()`, as
PR 9153 "Require plugins to succeed after registering readiness"
was merged on 2023-09-29.
Fix issue 9163: `[Regression in main (2023-09-29)]: containerd-rootless.sh doesn't start up`
Signed-off-by: Akihiro Suda <akihiro.suda.cz@hco.ntt.co.jp>