Validate config_db.json in reload path.

[dypet]

What I did

Fix for sonic-net/sonic-buildimage#27178 . /etc/sonic/config_db.json was not validated in the config reload path before loading. If a config that did not conform to schema was partially loaded, the system could end up in a bad unrecoverable state.

How I did it

added a config_file_yang_validation check to config_db.json in config reload path.

How to verify it

'config reload -y' after copying an invalid config to /etc/sonic/config_db.json.

Previous command output

:~$ sudo config reload -y
Acquired lock on /etc/sonic/reload.lock
Disabling container and routeCheck monitoring ...
Stopping SONiC target ...
Running command: /usr/local/bin/sonic-cfggen -j /etc/sonic/init_cfg.json -j /etc/sonic/config_db.json --write-to-db
Traceback (most recent call last):
  File "/usr/local/bin/sonic-cfggen", line 542, in <module>
    main()
    ~~~~^^
  File "/usr/local/bin/sonic-cfggen", line 531, in main
    configdb.mod_config(FormatConverter.output_to_db(data))
    ~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3/dist-packages/swsscommon/swsscommon.py", line 2862, in mod_config
    raw_data = self.typed_to_raw(data)
  File "/usr/lib/python3/dist-packages/swsscommon/swsscommon.py", line 2797, in typed_to_raw
    elif len(typed_data) == 0:
         ~~~^^^^^^^^^^^^
TypeError: object of type 'int' has no len()
Released lock on /etc/sonic/reload.lock

Config is partially loaded in this case, leaving system in state that needs to be recovered with

sudo cp config_db.json_working /etc/sonic/config_db.json
sudo sonic-db-cli CONFIG_DB SET CONFIG_DB_INITIALIZED 1
sudo config reload -y -f

New command output

:~$ sudo config reload -y
Acquired lock on /etc/sonic/reload.lock
sonic_yang(3):All Keys are not parsed in DASH_HA_GLOBAL_CONFIG
dict_keys(['cp_data_channel_port', 'dp_channel_dst_port', 'dp_channel_src_port_min', 'dp_channel_src_port_max', 'dp_channel_probe_interval_ms', 'dp_channel_probe_fail_threshold', 'dpu_bfd_probe_interval_in_ms', 'dpu_bfd_probe_multiplier', 'dpu_vnet', 'dpu_vlan'])
sonic_yang(3):exceptionList:[]
sonic_yang(3):Data Loading Failed:All Keys are not parsed in DASH_HA_GLOBAL_CONFIG
dict_keys(['cp_data_channel_port', 'dp_channel_dst_port', 'dp_channel_src_port_min', 'dp_channel_src_port_max', 'dp_channel_probe_interval_ms', 'dp_channel_probe_fail_threshold', 'dpu_bfd_probe_interval_in_ms', 'dpu_bfd_probe_multiplier', 'dpu_vnet', 'dpu_vlan'])
exceptionList:[]
/etc/sonic/config_db.json fails YANG validation! Error: Data Loading Failed
All Keys are not parsed in DASH_HA_GLOBAL_CONFIG
dict_keys(['cp_data_channel_port', 'dp_channel_dst_port', 'dp_channel_src_port_min', 'dp_channel_src_port_max', 'dp_channel_probe_interval_ms', 'dp_channel_probe_fail_threshold', 'dpu_bfd_probe_interval_in_ms', 'dpu_bfd_probe_multiplier', 'dpu_vnet', 'dpu_vlan'])
exceptionList:[]
Released lock on /etc/sonic/reload.lock
Aborted!

The incorrect config is not loaded in this case and system stays up.

[mssonicbld]

/azp run

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[mssonicbld]

/azp run

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[zjswhhh]

Hi @qiluo-msft - please help review and merge.