sync-images: failing due to ratelimiting in dockerhub

sync-images: failing due to ratelimiting in dockerhub

So trying to authenticate which might increase the ratelimit

https://jenkins.ceph.com/job/sync-images/651/console
```
Copying image sha256:a99b7d9812dbb7527eab8161807e879c3e66951ddccf21c5302061a651289da6 (15/16)
time="2025-12-25T20:16:10Z" level=fatal msg="Error copying ref \"docker://nginx:1.27.4\": copying image 15/16 from manifest list: determining manifest MIME type for docker://nginx:1.27.4: reading manifest sha256:a99b7d9812dbb7527eab8161807e879c3e66951ddccf21c5302061a651289da6 in docker.io/library/nginx: toomanyrequests: You have reached your unauthenticated pull rate limit. https://www.docker.com/increase-rate-limit"
Build step 'Execute shell' marked build as failure
```

Signed-off-by: Nizamudeen A <nia@redhat.com>