[Yang] Update Yang for pfc_enable and pfcwd_sw_enable fields

[bingwang-ms]

Why I did it

This PR is to update Yang model for pfc_enable and pfcwd_sw_enable fields to support more than 2 queues, like 2,3,4,6.
Before this change, the regex "[0-7](,[0-7])?" accepts only no more than 2 queues.

How I did it

Update the regex pattern for pfc_enable and pfcwd_sw_enable, from "[0-7](,[0-7])?" to "[0-7](,[0-7])*

How to verify it

The change is verified by UT. The test input is updated to cover the change.

collected 3 items                                                                                                                                                                                     

tests/test_sonic_yang_models.py ..                                                                                                                                                              [ 66%]
tests/yang_model_tests/test_yang_model.py .                                                                                                                                                     [100%]

====================================================================================== 3 passed in 2.55 seconds =======================================================================================

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

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

Description for the changelog

Update Yang model for pfc_enable and pfcwd_sw_enable fields to support more than 2 queues, like 2,3,4,6.

Link to config_db schema for YANG module changes

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