[Cherry pick][SAI-PTF]Two fix for sai-ptf infra

[richardyu-ms]

[SAI-PTF] Enhance the function for getting counters in sai_adapter.py (#1626)

* [SAI-PTF] Enhance the function for getting counters in sai_adapter.py

    Resolve issue #1614

    For the auto-generated adapter, need to add a parameter for which counter_id/counter_ids we want, in order to compatiable with current code and reduce the modification, we can define a constant parameter as the list of counter_ids, and use this constant as the default.

    Before

    ```
    def sai_thrift_get_bfd_session_stats(client,
                                         bfd_session_oid):

        counter_ids = []
        counter_ids.append(SAI_BFD_SESSION_STAT_IN_PACKETS)
        counter_ids.append(SAI_BFD_SESSION_STAT_OUT_PACKETS)
        counter_ids.append(SAI_BFD_SESSION_STAT_DROP_PACKETS)

        counters = [0] * 3
        global status
        status = SAI_STATUS_SUCCESS
    ```

    After the refactor
    ```
    sai_get_bfd_session_stats_counter_ids = []
    sai_get_bfd_session_stats_counter_ids.append(SAI_BFD_SESSION_STAT_IN_PACKETS)
    sai_get_bfd_session_stats_counter_ids.append(SAI_BFD_SESSION_STAT_OUT_PACKETS)
    sai_get_bfd_session_stats_counter_ids.append(SAI_BFD_SESSION_STAT_DROP_PACKETS)

    def sai_thrift_get_bfd_session_stats(client,
                                         bfd_session_oid,
                                         counter_ids=sai_get_bfd_session_stats_counter_ids):

        counters = [0] * 3
        global status
        status = SAI_STATUS_SUCCESS

[SAI-PTF] Add decorator for skipping test on specified error (#1609)

* [SAI-PTF] Add decorator for skipping test on specified error

Add decorator method in the perl template  for skipping test on specified error

details:
1. add decorator method in sai_adapter_utils.tt
2. use decorator when set parameters ``skip_error``
3. add parameters when building from template, like ``perl -Irpc gensairpc.pl  --skip_error=-2,-3``
4. remove the new added parameters, add more doc
Test done:
make  rpc