OCPBUGS-58324: podman-etcd Add OOM score adjustment for etcd containers

This change introduces a new oom parameter to the podman-etcd OCF
agent. This allows tuning the Out-Of-Memory (OOM) score adjustment for
the etcd container.

The oom parameter accepts integer values from -1000 to 1000,
defaulting to -997 (system-node-critical equivalent).

see https://kubernetes.io/docs/concepts/scheduling-eviction/node-pressure-eviction/#node-out-of-memory-behavior

Key changes:

• Added OCF_RESKEY_oom parameter to agent definition (content type="integer").
• Integrated --oom-score-adj option into podman_start().
• Implemented input validation for oom in podman_validate(), ensuring values are within the [-1000:1000] range.