[db_migrator] Fix parse_xml fails when minigraph has SonicQosProfile (#3972)

This change is to fix #22120 "Bug: [db_migrator] parse_xml fails when minigraph has SonicQosProfile".

If there is `SonicQosProfile` in minigraph.xml, parse_xml fails with below error:

2025 Jul 14 06:49:23.590302 vlab-01 ERR db_migrator: Caught exception while trying to parse minigraph: join() argument must be str, bytes, or os.PathLike object, not 'NoneType'

It's because select_mmu_profiles needs platform.
https://github.com/sonic-net/sonic-buildimage/blob/master/src/sonic-config-engine/minigraph.py#L1925

This change added code to get platform info. While calling `parse_xml`, pass in the `platform` argument.

Signed-off-by: Xin Wang <xiwang5@microsoft.com>

Author: wangxin

scripts/db_migrator.py

@@ -64,6 +64,8 @@ def __init__(self, namespace, socket=None):
         self.TABLE_KEY       = 'DATABASE'
         self.TABLE_FIELD     = 'VERSION'
 
+        self.platform = device_info.get_platform_info().get('platform')
+
         # Generate config_src_data from minigraph and golden config
         self.generate_config_src(namespace)
 
@@ -135,7 +137,7 @@ def generate_config_src(self, ns):
         minigraph_data = None
         try:
             if os.path.isfile(MINIGRAPH_FILE):
-                minigraph_data = parse_xml(MINIGRAPH_FILE)
+                minigraph_data = parse_xml(MINIGRAPH_FILE, platform=self.platform)
         except Exception as e:
             log.log_error('Caught exception while trying to parse minigraph: ' + str(e))
             pass