[GCU] Update RDMA Platform Validator

[isabelmsft]

What I did

ADO 24509483
-Fix RDMA platform validator PR to consider two edge cases:

1. Allow empty string value "" when the operation is remove in jsonpatch. Previously, empty string was not an allowed value, so these remove operations were incorrectly blocked. This is fixed by adding the empty string "" in the platform validator conf file for RDMA tables where remove operation is supported (only PFC_WD).
2. Ensure proper string parsing for an edge case jsonpatch path and value combination. The edge case combination is: the path includes contains a variable digit (such as /PFC_WD/Ethernet64 where 64 is the variable digit) and value is a dict. In this scenario, we need to clean the path and value combination differently so that the relevant value is properly extracted without an extra "/".

-add support for Mellanox spc2, spc3 asic

How I did it

Update GCU x RDMA platform validator functionality

How to verify it

E2E testing, test_add_rack passes

============================= test session starts ==============================
platform linux2 -- Python 2.7.18, pytest-4.6.11, py-1.11.0, pluggy-0.13.1
ansible: 2.8.12
rootdir: /data/sonic-mgmt-int/tests, inifile: pytest.ini
plugins: metadata-1.11.0, allure-pytest-2.8.22, html-1.22.1, xdist-1.28.0, forked-1.3.0, celery-4.4.7, repeat-0.9.1, ansible-2.2.4
['conf-name', 'group-name', 'topo', 'ptf_image_name', 'ptf', 'ptf_ip', 'ptf_ipv6', 'server', 'vm_base', 'dut', 'inv_name', 'auto_recover', 'comment']
Finished testbed info generating.
collected 1 item

configlet/test_add_rack.py::test_add_rack PASSED                         [100%]

test_pfcwd_status

============================= test session starts ==============================
platform linux2 -- Python 2.7.18, pytest-4.6.11, py-1.11.0, pluggy-0.13.1
ansible: 2.8.12
rootdir: /data/sonic-mgmt-int/tests, inifile: pytest.ini
plugins: metadata-1.11.0, allure-pytest-2.8.22, html-1.22.1, xdist-1.28.0, forked-1.3.0, celery-4.4.7, repeat-0.9.1, ansible-2.2.4
['conf-name', 'group-name', 'topo', 'ptf_image_name', 'ptf', 'ptf_ip', 'ptf_ipv6', 'server', 'vm_base', 'dut', 'inv_name', 'auto_recover', 'comment']
Finished testbed info generating.
collected 4 items

generic_config_updater/test_pfcwd_status.py::test_stop_pfcwd[single] PASSED [ 25%]
generic_config_updater/test_pfcwd_status.py::test_stop_pfcwd[all] PASSED [ 50%]
generic_config_updater/test_pfcwd_status.py::test_start_pfcwd[single] PASSED [ 75%]
generic_config_updater/test_pfcwd_status.py::test_start_pfcwd[all] PASSED [100%]

---------- generated xml file: /data/sonic-mgmt-int/tests/logs/tr.xml ----------

Previous command output (if the output of a command-line utility has changed)

New command output (if the output of a command-line utility has changed)

[qiluo-msft]

if

It's better to use if-else block. Single line is too long. #Closed

[isabelmsft]

Changed to if-else block

[jarias-lfx]

/easycla

[StormLiangMS]

@isabelmsft ADO?