[Thinkit] Add packet index to L3 admit tests to debug packet drops, Increase error tolerance slightly to 4%, Wait till counter is is updated to required value, Skip test if control plane bandwidth is lesser than queue rate, Buffer config needs to be allocated equally to validate scheduler & Clearing tables during config setup is best effort.

[Thinkit] Add packet index to L3 admit tests to debug packet drops, Increase error tolerance slightly to 4%, Wait till counter is is updated to required value, Skip test if control plane bandwidth is lesser than queue rate, Buffer config needs to be allocated equally to validate scheduler & Clearing tables during config setup is best effort. #4368