zebra: evpn entries are not cleaned upon frr stop

zebra: evpn entries are not cleaned upon frr stop

As part of PR 4458, when a client (bgpd) goes down,
zebra cleans up any evpn state including remotely learned
neighs, macs and vteps are suppose to be cleaned up,
uninstall from kernel tables.

Neighs (arps), macs and vteps (HREP entries) were not
removed from kernel tables as the uninstall flag as not set.

Clean up l3vni associated remote neighs, macs and vteps.

Ticket:CM-25468
Reviewed By:CCR-8889
Testing Done:

Validated in evpn symmetric routing topology where
remotely learned l2/l3 vnis neigh, macs and remote
vtep (hrep) entries are installed in kernel table,
perform systemctl stop frr.service and validated
all remotely learned entries cleaned up from kernel
tables.

Signed-off-by: Chirag Shah <chirag@cumulusnetworks.com>