fix(sync): request rdb-only replication when sync_aof is false

* test(sync): add rdb-only focused regression

Assisted-by: Codex:gpt-5.5

* fix(sync): request rdb-only replication

Assisted-by: Codex:gpt-5.5

* chore(ci): remove rdb-only focused workflow

Assisted-by: Codex:gpt-5.5

* fix(sync): simplify rdb-only replconf handling

Assisted-by: Codex:gpt-5.5

Author: DCjanus

internal/reader/sync_standalone_reader.go

@@ -246,6 +246,9 @@ func (r *syncStandaloneReader) sendPSync() {
 			r.isDiskless = true
 		}
 	}
+	if !r.opts.SyncAof {
+		r.sendReplconfRDBOnly()
+	}
 	r.checkBgsaveInProgress()
 	// send PSync
 	argv := []interface{}{"PSYNC", "?", "-1"}
@@ -282,6 +285,19 @@ func (r *syncStandaloneReader) sendPSync() {
 	r.stat.AofReceivedOffset = int64(masterOffset)
 }
 
+func (r *syncStandaloneReader) sendReplconfRDBOnly() {
+	argv := []interface{}{"REPLCONF", "rdb-only", "1"}
+	r.client.Send(argv...)
+	_, err := r.client.Receive()
+	if err != nil {
+		var redisErr proto.RedisError
+		if errors.As(err, &redisErr) {
+			return
+		}
+		log.Panicf("[%s] send replconf rdb-only to redis server failed. error=[%v]", r.stat.Name, err)
+	}
+}
+
 func (r *syncStandaloneReader) sendSync() {
 	if r.opts.TryDiskless {
 		argv := []interface{}{"REPLCONF", "CAPA", "EOF"}