boltstore logs to stdout: adopt hclog logger from Raft

[hermanbanken]

We have configured JSON loggers in all of our projects, but boltstore logs to stdout directly with <timestamp> Rollback failed: tx closed many times. I believe it happens before a StatefulSet shuts down an instance of our raft cluster. On startup of the new pod I see "found temporary snapshot", also many times. I'm not sure if those two things are related, or whether it is actually an issue at all. Everything seems to work fine & recover from the rollout fine.

The plaintext error originates from:

raft-boltdb/bolt_store.go

Line 103 in 8f7048c

log.Printf("Rollback failed: %v", err)

// found temporary snapshot logs:
caller: "raft@v1.7.2/file_snapshot.go:228"
message: "found temporary snapshot"
name: "71829-100912556-1739642499416.tmp"

Versions:

	github.com/hashicorp/raft v1.3.1
	github.com/hashicorp/raft-boltdb v0.0.0-20210422161416-485fa74b0b01