change/sonic replace instead of merge

[h4ndzdatm0ld]

Changed config load to config replace in sonic/docker/backup.sh to ensure user-provided startup configurations completely replace the default config instead of merging with it. This provides deterministic, predictable device configurations when deploying SONIC containers with custom config_db.json files.

[hellt]

thanks @h4ndzdatm0ld

let me check with the original PR author if there was a use case behind the merge behavior

@adam-kulagowski, do you remember why you went with load and not replace?

[adam-kulagowski]

Nothing comes to my mind - unfortunately it was over a year ago. Replace do sounds like a better approach though :)