Zebra: Fix replace route for uninstall scenario

Zebra: Fix replace route for uninstall scenario

When a Quagga route that is currently installed is superceded by a
kernel route (connected or static route to same destination), the
Quagga route is not uninstalled from the kernel. Fix by ensuring
this case is handled correctly.

Signed-off-by: Vivek Venkatraman <vivek@cumulusnetworks.com>
Reviewed-by:   Donald Sharp <sharpd@cumulusnetworks.com>
Ticket: CM-7152
Reviewed By: CCR-3476
Testing Done: Manual tests and verify failed test.

Fixes: Replace route implementation (IPv4 and IPv6)