chore: reduce log level in handleDiscover

[richard-ramos]

This PR changes the log level from INFO to DEBUG, for a log line within handleDiscover function, since this function is executed frequently in rendezvous points, and this line ends up adding too much noise when browsing logs

example: 

2023-03-13T20:42:19.987-0400    INFO    rendezvous      go-libp2p-rendezvous@v0.4.1/svc.go:234  discover query: 16Uiu2HAmG4jyX7gz2MVHzeczDvHa5owG9H7Liu7RAXS2DHG1r8Hm /waku/2/default-waku/proto -> 1   {"node": "16Uiu2HAmMGhfSTUzKbsjMWxc6T1X4wiTWSF1bEWSLjAukCm7KiHV"}