Update MMU and ECN settings for T2 chassis

[vmittal-msft]

Why I did it

1. Update per VSQ headroom size based on port speed/cable length for uplink and downlink ports - Done
2. Update total headroom pool size based on uplink/downlink line card type - Done
3. Update ECN settings for 2MB/10MB/5% (min/max/drop probability) - Done
4. Update dynamic threshold (alpha) to limit max VoQ length based on production settings.
5. Remove any reserved space per VSQ/VoQ as low alpha value will protect buffer starvation for different flows.
6. Update VoQ drop threshold to max. VSQ drop/flow control threshold to be used for buffer management.

How I did it

How to verify it

Which release branch to backport (provide reason below if selected)

• 201811
• 201911
• 202006
• 202012
• 202106
• 202111
• 202205
• 202211

Description for the changelog

Ensure to add label/tag for the feature raised. example - PR#2174 under sonic-utilities repo. where, Generic Config and Update feature has been labelled as GCU.

Link to config_db schema for YANG module changes

A picture of a cute animal (not mandatory but encouraged)