[config db] Trim garbage charactor in "DEVICE_METADATA" of config db (sonic-net#3345)

the garbage char could be generated with "load_minigraph" if '-override-config' is specified, and if golden_config has garbage char.
it could also be introduced by "config reload"

Author: wenyiz2021

config/main.py

@@ -2206,8 +2206,8 @@ def generate_sysinfo(cur_config, config_input, ns=None):
     if not platform:
         platform = device_info.get_platform()
 
-    device_metadata['localhost']['mac'] = mac
-    device_metadata['localhost']['platform'] = platform
+    device_metadata['localhost']['mac'] = mac.rstrip('\n')
+    device_metadata['localhost']['platform'] = platform.rstrip('\n')
 
     return
 

tests/config_override_test.py

@@ -386,10 +386,10 @@ def read_json_file_side_effect(filename):
 
         with mock.patch('config.main.read_json_file',
                         mock.MagicMock(side_effect=read_json_file_side_effect)),\
-                mock.patch('sonic_py_common.device_info.get_platform',
+             mock.patch('sonic_py_common.device_info.get_platform',
                         return_value="multi_asic"),\
-                mock.patch('sonic_py_common.device_info.get_system_mac',
-                        return_value="11:22:33:44:55:66"):
+             mock.patch('sonic_py_common.device_info.get_system_mac',
+                        return_value="11:22:33:44:55:66\n"):
             runner = CliRunner()
             result = runner.invoke(config.config.commands["override-config-table"],
                                    ['golden_config_db.json'], obj=db)