fix(dns): spam ttl logs for prepared queries (#21381)

.changelog/21381.txt

@@ -0,0 +1,4 @@
+```release-note:bug
+dns: Fixes a spam log message "Failed to parse TTL for prepared query..."
+that was always being logged on each prepared query evaluation.
+```

agent/discovery/query_fetcher_v1.go

@@ -363,12 +363,13 @@ func (f *V1DataFetcher) FetchPreparedQuery(ctx Context, req *QueryPayload) ([]*R
 		if err == nil {
 			ttlSec := uint32(ttl / time.Second)
 			ttlOverride = &ttlSec
-		}
+		} else {
 			f.logger.Warn("Failed to parse TTL for prepared query , ignoring",
 				"ttl", out.DNS.TTL,
 				"prepared_query", req.Name,
 			)
 		}
+	}
 
 	// If we have no nodes, return not found!
 	if len(out.Nodes) == 0 {