raft: `raftlogger` and `rafttest` should use `pkg/util/log` instead of stdlib `log` package

This lint failure was uncovered when #132258 was addressed:

```
github.com/cockroachdb/cockroach/pkg/raft/raftlogger: log <- please use "util/log" instead of "log"
```

Attempting to follow this advice results in the following:

```
pkg/raft/raftlogger/logger.go:63:49: undefined: log.New
pkg/raft/raftlogger/logger.go:63:76: undefined: log.LstdFlags
pkg/raft/raftlogger/logger.go:64:49: undefined: log.New
pkg/raft/raftlogger/logger.go:75:7: undefined: log.Logger
pkg/raft/raftlogger/logger.go:89:5: l.Output undefined (type *DefaultLogger has no field or method Output)
pkg/raft/raftlogger/logger.go:95:5: l.Output undefined (type *DefaultLogger has no field or method Output)
pkg/raft/raftlogger/logger.go:108:4: l.Output undefined (type *DefaultLogger has no field or method Output)
pkg/raft/raftlogger/logger.go:112:4: l.Output undefined (type *DefaultLogger has no field or method Output)
pkg/raft/raftlogger/logger.go:124:4: l.Output undefined (type *DefaultLogger has no field or method Output)
pkg/raft/raftlogger/logger.go:129:4: l.Output undefined (type *DefaultLogger has no field or method Output)
pkg/raft/raftlogger/logger.go:129:4: too many errors
```

So some refactoring is necessary here.

For now we will exempt this in the lint check.

There is also an issue with `rafttest` (fails to find a function `log.Printf()`)

Jira issue: CRDB-42906

Start with pkg/raft/raftlogger/logger.go and inspect how its stdlib log.Logger, log.New, log.LstdFlags, and Output calls map to pkg/util/log. Then inspect rafttest for its log.Printf usage and the lint exemption added for these packages. Done means both packages use pkg/util/log, compile without the reported errors, and no longer require the lint exemption.

Written by the indexing model from the issue text.