Update SSH key for shark

Summary:
The key used SHA-1 algo, not supported by recent OpenSSH recommendations
and current server configurations.

After debugging on IRC, a new ed25519 has been created to solve the issue.

This fixes the following issue:
2025-11-09T15:35:05.633129+00:00 zonegrey sshd-session[674317]:
userauth_pubkey: signature algorithm ssh-rsa not in PubkeyAcceptedAlgorithms [preauth]

Fixes T2182.

Test Plan: ssh shark@eglide.org

Reviewers: dereckson

Subscribers: shark

Maniphest Tasks: T2182

Differential Revision: https://devcentral.nasqueron.org/D3861