[Do not merge] raft: use fast restore by default

[schmichael]

This is just a test of hashicorp/raft#613 and not intended for merging as-is.

Since there is no corresponding raft-boltdb implementation, it's not possible to functionally test this change as-is.

A final implementation should allow users to opt-out in case of bugs or unforeseen downsides.

Logs of non-dev agent's:

==> Starting Nomad agent...
==> Error starting agent: server setup failed: Failed to start Raft: log store does not implement some required methods or malformed
    2025-03-31T11:31:34.763-0700 [DEBUG] nomad: issuer not set; OIDC Discovery endpoint for workload identities disabled
    2025-03-31T11:31:34.770-0700 [INFO]  nomad: setting up raft bolt store: no_freelist_sync=false
    2025-03-31T11:31:34.772-0700 [WARN]  nomad.raft: restore committed logs enabled but log store does not support it: log_store="*raft.LogCache"
    2025-03-31T11:31:34.772-0700 [INFO]  nomad: shutting down server
    2025-03-31T11:31:34.772-0700 [ERROR] nomad: failed to start Raft: error="log store does not implement some required methods or malformed"
    2025-03-31T11:31:34.772-0700 [ERROR] agent: error starting agent: error="server setup failed: Failed to start Raft: log store does not implement some required methods or malformed"

Description

Update raft to restore from local committed logs before streaming.

Testing & Reproduction steps

TODO

Links

hashicorp/raft#613

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