[202405] Added Change for given Route ECMP to fallback on Default Route ECMP

[abdosi]

What I did:

Cherry-pick of PR: sonic-net/sonic-swss#3389

[abdosi]

@arlakshm pls help with signoff/review

[arlakshm]

@abdosi the codeQL is failing with this error can you please check if this ok?

Switched to a new branch 'sonic'
error: patch failed: lib/route/route_obj.c:1201
error: lib/route/route_obj.c: patch does not apply
stg import: Diff does not apply cleanly

[prsunny]

@abdosi , can this be going to 202411 instead? Seems like a major change for 202405 branch. @bingwang-ms for viz. Is this dedicated repo?

[abdosi]

@abdosi , can this be going to 202411 instead? Seems like a major change for 202405 branch. @bingwang-ms for viz. Is this dedicated repo?

yes @prsunny this PR is in sonic-swss.msft repo and will be used by Chassis only. We will not take this in 202405.