Json log contains non json lines

### Nomad version
1.7.3

### Operating system and Environment details
Ubunu 22.04

### Issue
Json log contains non json lines which creates a problem with parsing and logshipping

Configration:
```
log_level = "INFO"
log_json = true
log_file = "/var/log/nomad/"
log_rotate_max_files = 7
```

Log output:
```
{"@level":"info","@message":"starting snapshot up to","@module":"nomad.raft","@timestamp":"2024-03-07T07:42:17.145421+01:00","index":667715}
2024-03-07T07:42:17.146+0100 [INFO] snapshot: creating new snapshot: path=/opt/nomad/server/raft/snapshots/1731-667715-1709793737146.tmp
2024-03-07T07:42:17.774+0100 [INFO] snapshot: reaping snapshot: path=/opt/nomad/server/raft/snapshots/1731-651310-1709279390798
{"@level":"info","@message":"compacting logs","@module":"nomad.raft","@timestamp":"2024-03-07T07:42:17.779955+01:00","from":649263,"to":657475}
```