fix: dedup gauge (#6359)

# Description

Fixing dedup gauge.

## Linear Ticket

Fixes
[PIPE-2402](https://linear.app/rudderstack/issue/PIPE-2402/fix-rudder-server-dedup-gauge)

## Security

- [x] The code changed/added as part of this pull request won't create
any security issues with how the software is being used.

Author: fracasula

services/dedup/db.go

@@ -79,7 +79,7 @@ func NewDB(conf *config.Config, s stats.Stats, log logger.Logger) (types.DB, err
 		modeGauge("keydb", "badger")
 		return NewMirrorDB(primary, mirror, mirrorToBadger, conf, s, log), nil
 	default:
-		modeGauge("keydb", "none")
+		modeGauge("badger", "none")
 		log.Warnn("Invalid mirror mode, falling back to badger only")
 		// Default to badger only
 		return badger.NewBadgerDB(conf, s, badger.DefaultPath())