If leader can't load snapshot cluster won't recover

Hello folks! I have a pretty lazy bug report here so apologies for not going deeper but I wanted to float a stance that by you and see if I can get away with it

We had a cluster of nomad servers that lost quorum and would not elect a new leader

Looking at the logs, the leader at the time was logging this

```
2022-08-17T03:11:20.634Z 2022-08-17T03:11:20.634Z [ERROR] snapshot: failed to get snapshots: error="open /run/nomad-server/server/raft/snapshots: no such file or directory"
2022-08-17T03:11:20.634Z 2022-08-17T03:11:20.634Z [ERROR] snapshot: failed to scan snapshot directory: error="open /run/nomad-server/server/raft/snapshots: no such file or directory"
2022-08-17T03:11:20.634Z failed to send snapshot to
2022-08-17T03:11:20.634Z failed to list snapshots
2022-08-17T03:11:20.634Z failed to get log
2022-08-17T03:11:20.608Z failed to list snapshots
2022-08-17T03:11:20.608Z failed to send snapshot to
```

And other servers were logging this
```
2022-08-17T03:07:55.677Z error waiting for Raft index error=timed out after 5s waiting for index=1525203
```

So here is my stance:
If the leader is broken because it cannot load the snapshots (I have no idea how we got in this situation but lets ignore that for now); the other server should realize the leader is useless and usurp him; perhaps via invoking the Praetorians Guard.

or more down to Earth: this state should cause a heartbeat failure in some way so that we can move past it and elect a new leader.

What do you think?

Start by tracing the snapshot-loading failure from the reported missing snapshots directory into Raft heartbeat and leader-election handling. Reproduce the condition if possible using the logged errors, then determine whether a leader that cannot serve snapshots should trigger failure detection and a new election. Done means the failure mode is handled consistently and covered by an appropriate test.

Written by the indexing model from the issue text.