I have added the ability to use mDNS repeater along with VRRP in the attached PR. This would allow the mDNS repeater to be enabled on VRRP-enabled routers as only the master router will repeat the packets.
It can be enabled with: set service mdns repeater disable-on-vrrp
When the setting is active mDNS repeater will disable mDNS on interfaces where VRRP is active and the state is not MASTER. A hook is also added to keepalived_fifo to keep the mDNS repeater updated as VRRP states change.