[T2-Chassis][Route-Convergence]: route-convergence takes upto 10secs in Process crash(swss/syncd) scenarios

[deepak-singhal0408]

On T2 Chassis, running 202405 image, process crash takes upto 10 seconds for traffic to converge. It needs to be optimized. Ideally, we should achieve subsecond convergence in this scenario..

Testplan:
https://github.com/sonic-net/sonic-mgmt/blob/master/docs/testplan/Convergence%20measurement%20in%20data%20center%20networks.md#test-case--26

Number of prefixes:
60k(30k V4+30k v6) from each Upstream Neighbors

Number of Upstream Neighbors: 16

Testcase:
https://github.com/sonic-net/sonic-mgmt/blob/master/tests/snappi_tests/multidut/bgp/test_bgp_outbound_uplink_process_crash.py

[deepak-singhal0408]

The observation is that traffic loss is observed when these processes are coming up.. They start learning routes from their neighbors(upstream) and immediately start advertising to their other neighbors(downstream) and start attracting traffic even before programming them in their asics.